Last visit was: 18 Nov 2025, 22:39 It is currently 18 Nov 2025, 22:39
Close
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Close
Request Expert Reply
Confirm Cancel
User avatar
andreagonzalez2k
Joined: 15 Feb 2021
Last visit: 26 Jul 2025
Posts: 308
Own Kudos:
497
 [1]
Given Kudos: 14
Posts: 308
Kudos: 497
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
harshnaicker
Joined: 13 May 2024
Last visit: 25 Sep 2025
Posts: 84
Own Kudos:
60
 [1]
Given Kudos: 35
Posts: 84
Kudos: 60
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
Mardee
Joined: 22 Nov 2022
Last visit: 16 Oct 2025
Posts: 127
Own Kudos:
110
 [1]
Given Kudos: 17
Products:
Posts: 127
Kudos: 110
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
GarvitGoel
Joined: 06 Aug 2024
Last visit: 17 Nov 2025
Posts: 69
Own Kudos:
54
 [1]
Posts: 69
Kudos: 54
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Option E is the correct answer.

Lets understand the information mentioned in the question before try to solve for it.

So the question starts by telling us that Mark has loaded a total of 80 boxes in his 4 hour shift. And then asks us was the average (arithmetic mean) weight of the boxes he loaded during the shift.

Now after understanding the information mentioned in the question lets check the given statements and see whether we can find out the answer with their help or not.

Statement 1: "During the first 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 20 kilograms". Now this statement tells us that during the first 2 hours of his shift the average weight of the boxes which he loaded was 20 kg but does not gives us any information about second haft of the shift or the actual number of box which he loaded in this duration. So from here we can have multiple cases like: lets say he loaded 40 boxes in the first half and in the second half also he loaded 40 boxes of the same average i.e. 20 kg then this will give us the total average weight of 20 kg. Whereas we take that in the first half he loaded 30 boxes and in the second half he loaded 50 boxes of average weight 25 kg then the overall average will be: (20*30+50*25)/80 = 23.125 kg. So from these two cases only we can tell that we are getting multiple answers from this piece of information that's why this is Not Sufficient to answer the question.


Statement 2: "During the last 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 30 kilograms". This statement also the same as the first statement it only gives us the average weight for second half of the shift but does not give any specific number of boxes or the average weight for first half. So as we checked for the first statement this statement will also give as multiple values that's why this is also Not Sufficient to answer the question.


As we have checked that both the statements alone cannot answer the question so now lets try to Combine both of then and see whether we can find our answer from their Combination or not.

So after combination we know the average weight of the boxes which were loaded in first half of the shift is 20 kg and average weight of the boxes which were loaded in second half of the shift is 30 kg.
Now lets assume the number of boxes loaded in first half to be 'x' then the number of boxes loaded in second half will be (80-x), it which will help us in easing the calculation part now.

Now to find the total average weight of the boxes we have to calculate: (20*x + 30*(80-x)/80
Lets assume x to be 40 then (80-x) will also be 40. Now lets put these values in the above equation.
=>(20*40+30*40)/80 = 25 kg.

Now lets assume the value of x to be 60 then the value of (80-x) will be 20, lets see whether we get the same average in this case as well or not.
=>(20*60+30*20)/80 = 22.5 kg

As we can clearly see that here also we are not getting any unique value to the question that's why we can conclude that neither Statement-1 nor Statement-2 are sufficient to answer the question and the Combination is also Not Sufficient to answer the question. That's why Option E is our answer.

Bunuel
Over a 4-hour shift, Mark loaded a total of 80 boxes into a truck. What was the average (arithmetic mean) weight of the boxes he loaded during the shift?

(1) During the first 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 20 kilograms.
(2) During the last 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 30 kilograms.


 


This question was provided by GMAT Club
for the GMAT Club Olympics Competition

Win over $30,000 in prizes such as Courses, Tests, Private Tutoring, and more

 

User avatar
Punt
Joined: 09 Jul 2024
Last visit: 11 Nov 2025
Posts: 36
Own Kudos:
29
 [1]
Given Kudos: 15
Location: India
Posts: 36
Kudos: 29
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Even after all the information, we don’t know the number of boxes loaded in the periods. Neither in the first two hours, not in the last two hours.
So, even with the information provided in the both statements, we cannot determine the average weight of the total boxes.
Answer: E

Bunuel
Over a 4-hour shift, Mark loaded a total of 80 boxes into a truck. What was the average (arithmetic mean) weight of the boxes he loaded during the shift?

(1) During the first 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 20 kilograms.
(2) During the last 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 30 kilograms.


 


This question was provided by GMAT Club
for the GMAT Club Olympics Competition

Win over $30,000 in prizes such as Courses, Tests, Private Tutoring, and more

 

User avatar
LastHero
Joined: 15 Dec 2024
Last visit: 11 Nov 2025
Posts: 134
Own Kudos:
147
 [1]
Given Kudos: 1
Posts: 134
Kudos: 147
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
We have to find the total weight of the 80 boxes loaded during the 4-hour shift and divide the result by 80.

(1)
We have no information about the last 2 hours of the shift.

Statement is insufficient

(2)
We have no information about the first 2 hours of the shift.

Statement is insufficient

(1)+(2)
We need to calculate the total weight of the 80 boxes, that will be equal to the sum of the total weight of the boxes during the first 2 hours plus the total weight of the boxes during the last 2 hours, but:
- we cannot calculate the total weight of the boxes during the first 2 hours of the shift because we do not know the number of boxes that were loaded in those 2 hours.
- we cannot calculate the total weight of the boxes during the last 2 hours of the shift because we do not know the number of boxes that were loaded in those 2 hours.

Both statements are insufficient

The right answer is E
User avatar
Aarushi100
Joined: 17 Jul 2024
Last visit: 18 Nov 2025
Posts: 56
Own Kudos:
44
 [1]
Given Kudos: 88
Products:
Posts: 56
Kudos: 44
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
Over a 4-hour shift, Mark loaded a total of 80 boxes into a truck. What was the average (arithmetic mean) weight of the boxes he loaded during the shift?

(1) During the first 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 20 kilograms.
(2) During the last 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 30 kilograms.


 


This question was provided by GMAT Club
for the GMAT Club Olympics Competition

Win over $30,000 in prizes such as Courses, Tests, Private Tutoring, and more

 

For arithmetic mean we use the formula of weighted averages:

x(mean) = n1*x1+n2*x2/n1+n2
Here we know,
n1+n2=80

Statement 1:
We just get the value of x1 from this.
Still need the value of n1, n2 and x2 to find the mean
Not Sufficient.

Statement 2:
We just get the value of x2 from this.
Still need the value of n1, n2 and x1 to find the mean
Not Sufficient

Statement 1 and 2:
We still don't have the value of n1 and n2
We just know n1+n2=80
Not Sufficient.

ANSWER: E
User avatar
Praveena_10
Joined: 01 Jan 2024
Last visit: 18 Nov 2025
Posts: 36
Own Kudos:
36
 [1]
Given Kudos: 21
Location: India
GPA: 7.3
WE:Engineering (Energy)
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
80 Boxes were loaded in 4hour shift.

Statement 1- Avg weight of boxes loaded during first two hours is 20kg. From this we don't know how many boxes were loaded.
(2)Statement 2- Similar to the first statement we still dont know the number of boxes.

Both Statements combined-
let us assume n1 and n2 be the number of boxes loaded in first and second halfs.
n1+n2=80
20n1+30n2/n1+n2= average
20n1+30(80-n1)/n1+80-n1
2400-10n1/80
we still dont have any detail about n1. So both statements together are not sufficient.
User avatar
jkkamau
Joined: 25 May 2020
Last visit: 18 Nov 2025
Posts: 132
Own Kudos:
107
 [1]
Given Kudos: 122
Location: Kenya
Schools: Haas '25
GMAT 1: 730 Q50 V46
GPA: 3.5
Products:
Schools: Haas '25
GMAT 1: 730 Q50 V46
Posts: 132
Kudos: 107
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
To find mean weight = total weight divide by 80
S1 is insufficient because we have no info about no of boxes
S2 too is insufficient because we have no info about no of boxes
S1+S2
Assume first 2 hours he did x boxes meaning he did 80-x in the last two hours
Total weight would be 20x+30(80-x)= 2400-10x
so mean would be (2400-10x)/80 which is impossible to compute coz x is unknown hence both are insufficient
ANS E
Bunuel
Over a 4-hour shift, Mark loaded a total of 80 boxes into a truck. What was the average (arithmetic mean) weight of the boxes he loaded during the shift?

(1) During the first 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 20 kilograms.
(2) During the last 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 30 kilograms.


 


This question was provided by GMAT Club
for the GMAT Club Olympics Competition

Win over $30,000 in prizes such as Courses, Tests, Private Tutoring, and more

 

User avatar
Tanish9102
Joined: 30 Jun 2025
Last visit: 18 Nov 2025
Posts: 59
Own Kudos:
49
 [1]
Posts: 59
Kudos: 49
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Correct Answer: We can't find average (arithmetic mean) weight of the boxes he loaded during the shift.
Both the statements together and alone are not sufficient.


Let’s check each statement alone and together:

(1) During the first 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 20 kilograms.
Here we don't know exactly what number of boxes are of 20 kg weight. Even, we don't know about the number of boxes and their weights in last two hour. So without having either if these two information we can't use this statement alone.

(2) During the last 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 30 kilograms.
Similarly if we use this statement alone, we don't know about first two hours number of boxes and their weights. Also we don't know exactly what number of boxes are of 30 kg weight. So without having either if these two information we can't use this statement alone.

3) Using both the statements:

If we use both statements also, we can't answer this question.
Let’s check this using an example:
Suppose we have 50 boxes of 20kg weight and 30 boxes of 30Kg weight
Average= (1000 + 900)/ 4 hours= 475kg
Let's take another example,
Suppose we have 40 boxes of 20kg weight and 40 boxes of 30Kg weight
Average= (800 + 1200) / 4 hours= 500 kg

Hence we cannot solve this question using both the statement together.
User avatar
adityaprateek15
Joined: 26 May 2023
Last visit: 18 Nov 2025
Posts: 268
Own Kudos:
104
 [1]
Given Kudos: 309
Location: India
GPA: 2.7
Products:
Posts: 268
Kudos: 104
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Q: Avg. weight of the boxes?
Avg. weight of boxes = Total weight/Total boxes (80)
We need the total weight of these boxes.

St1: This statement does not tell us how many boxes were loaded during this period. Without the number of boxes, we cannot get the total weight of boxes loaded in the first 2 hours. Insufficient.

St2: Similarly, this statement gives us the average weight of boxes loaded in the last 2 hours but not the number of boxes loaded during this period. Thus, we cannot calculate the total weight for the last 2 hours. Insufficient.

Combing St1 and St2: Even after combining, we still don’t know the number of boxes loaded in the first 2 hours and the number of boxes loaded in the last 2 hours and the total weight of the 80 boxes.

Option E

Bunuel
Over a 4-hour shift, Mark loaded a total of 80 boxes into a truck. What was the average (arithmetic mean) weight of the boxes he loaded during the shift?

(1) During the first 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 20 kilograms.
(2) During the last 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 30 kilograms.


 


This question was provided by GMAT Club
for the GMAT Club Olympics Competition

Win over $30,000 in prizes such as Courses, Tests, Private Tutoring, and more

 

User avatar
vnar12
Joined: 03 Jun 2024
Last visit: 26 Aug 2025
Posts: 51
Own Kudos:
32
 [1]
Given Kudos: 4
Posts: 51
Kudos: 32
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
The correct answer is choice (E) both statements are not sufficient

Statement 1 - this provides information about the first 2 hours of the shift and and the 20 kg average of the boxes but we don't know how many boxes of the 80 were loaded in order to calculate the final average.

Statement 2 - similarly, this provides information about the second half of the shift and the 30 kg average but we don't know how many boxes of the 80 were loaded in this half.

Since the number of boxes within each shift half is important to calculate the average overall, we cannot solve the question without more information and both of those statements are not enough to solve it.
User avatar
ODST117
Joined: 15 Aug 2024
Last visit: 29 Oct 2025
Posts: 173
Own Kudos:
85
 [1]
Given Kudos: 149
Posts: 173
Kudos: 85
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Given -> 4 hour shift. Mark loaded 80 boxes
To determine -> Average weight of the 80 boxes.

Statement 1 -> During the first 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 20 kilograms.
Say the number of boxes loaded during these two hours is \(N\) and \(S_1\) is the sum of the weight of the boxes
\(\frac{S_1}{N} = 20\)
We don't know how many boxes were loaded in the next 2 hours nor do we know their weights. Insufficient.

Statement 2 -> During the last 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 30 kilograms.
Say the number of boxes loaded during these two hours is \(80-N\) and \(S_2\) is the sum of the weight of the boxes
\(\frac{S_2}{80-N} = 30\)

We don't know how many boxes were loaded in the first 2 hours nor do we know their weights. Insufficient.

1+2 -> The average weight of all the boxes \(= \frac{S_1+S_2}{80}\)
\(S_1=20N\)

\(S_2=30(80-N)\)

\(\frac{S_1+S_2}{80} = \frac{20N+30(80-N)}{80}\)

We don't know what \(N\) is. Not sufficient.

Answer - E
User avatar
eshika23
Joined: 01 Aug 2024
Last visit: 11 Oct 2025
Posts: 71
Own Kudos:
34
 [1]
Given Kudos: 65
Posts: 71
Kudos: 34
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Given:
Mark loaded 80 boxes in 4 hour shift

Question
Avg mean of weight during shift?

Statement 1: During the first 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 20 kilograms.
In first 2 hours of 4 hours shift he loaded boxes of avg weight 20 kg. But we dont know if his rate of work was similar throughout or different.
So this is not sufficient.

Statement 2: During the last 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 30 kilograms.
Same reason, we know last 2 hours but no idea on what was his rate of of work in first 2 hours.
So this is not sufficient.

Combine:
We know in first 2 hours he loaded boxes weighing 20kg avg, In last 2 hours he loaded boxes weighing 30kg avg.

But we dont know the quantity of how many boxes were loaded in each hour or we dont know the total weight of 80 goods.

What if he loaded 50 boxes in first 2 hours then 30 in next 2 hours
his rater will be 100+90/4=190/4=47.5 kg

If he loads 40 boxes in first 2 hours and 40 in next two hours
His rate will be 80+120/4=200/4=50 kg/box

So we cannot determine the exact weight.

So no statement is sufficient.
Answer E

Bunuel
Over a 4-hour shift, Mark loaded a total of 80 boxes into a truck. What was the average (arithmetic mean) weight of the boxes he loaded during the shift?

(1) During the first 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 20 kilograms.
(2) During the last 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 30 kilograms.


 


This question was provided by GMAT Club
for the GMAT Club Olympics Competition

Win over $30,000 in prizes such as Courses, Tests, Private Tutoring, and more

 

User avatar
RedYellow
Joined: 28 Jun 2025
Last visit: 09 Nov 2025
Posts: 80
Own Kudos:
74
 [1]
Posts: 80
Kudos: 74
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
To calculate average is necessary to know total weight of the 80 boxes.

(1)
It's impossible to calculate total weight of the 80 boxes.

Insufficient

(2)
It's impossible to calculate total weight of the 80 boxes.

Insufficient

(1) and (2)
Knowing parcial averages without knowing the number of boxes in each part, it is still impossible to calculate the total weight of the 80 boxes.

Insufficient

Correct answer is E
User avatar
HK12!
Joined: 04 Jul 2023
Last visit: 18 Nov 2025
Posts: 27
Own Kudos:
10
 [1]
Given Kudos: 18
Location: India
Concentration: Entrepreneurship, Sustainability
GMAT 1: 370 Q31 V12
GPA: 4
WE:Marketing (Other)
Products:
GMAT 1: 370 Q31 V12
Posts: 27
Kudos: 10
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Statement (1):
Average in first 2 hours = 20 kg
But we don’t know how many boxes were loaded in those 2 hours.
Not sufficient

Statement (2):
Average in last 2 hours = 30 kg
Again, no info on how many boxes in those 2 hours.
Not sufficient

Combine (1) and (2):
Still no info. on how many boxes in each half of the shift.
So we cannot compute total weight or average.
Still not sufficient.

So, the correct answer is option E
User avatar
Lemniscate
Joined: 28 Jun 2025
Last visit: 09 Nov 2025
Posts: 80
Own Kudos:
72
 [1]
Posts: 80
Kudos: 72
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
average = sum all boxes / 80

(1)
No information about sum all boxes.

Statement (1) alone is insufficient.

(2)
No information about sum all boxes.

Statement (2) alone is insufficient.

(1)+(2)
To calculate the sum of the 80 boxes, we would need to know how many boxes were loaded in the first 2 hours or in the second 2 hours. Since we don't know this, we can't calculate the total sum of the 80 boxes and, therefore, can't calculate the average for the 4 hours.

Statement (1) and (2) together are insufficient

Answer E
User avatar
bebu24
Joined: 19 May 2025
Last visit: 21 Aug 2025
Posts: 61
Own Kudos:
35
 [1]
Given Kudos: 12
Posts: 61
Kudos: 35
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Statement I:
If mark loads k1 boxes during first 2 hours:
20k1 = Sum of weights of k1 boxes.
We have no information about the avg. weight during last 2 hrs. Insufficient.

Statement II:
If mark loads k2 boxes during lasr 2 hours:
30k2 = Sum of weights of k2 boxes.
We have no information about the avg. weight during first 2 hrs. Insufficient.

Statement I and II:
Avg. weight = 20k1 + 30k2/80
We do not know k1 and k2. Therefore insufficient.

Therefore , option E is correct.
Bunuel
Quote:
Over a 4-hour shift, Mark loaded a total of 80 boxes into a truck. What was the average (arithmetic mean) weight of the boxes he loaded during the shift?

(1) During the first 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 20 kilograms.
(2) During the last 2 hours of the shift, the average (arithmetic mean) weight of the boxes Mark loaded was 30 kilograms.


 


This question was provided by GMAT Club
for the GMAT Club Olympics Competition

Win over $30,000 in prizes such as Courses, Tests, Private Tutoring, and more

 

User avatar
Suyash1331
Joined: 01 Jul 2023
Last visit: 20 Oct 2025
Posts: 118
Own Kudos:
61
 [1]
Given Kudos: 22
Location: India
GMAT Focus 1: 575 Q65 V70 DI70
GMAT 1: 250 Q20 V34
GPA: 7
Products:
GMAT Focus 1: 575 Q65 V70 DI70
GMAT 1: 250 Q20 V34
Posts: 118
Kudos: 61
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
the answer is clearly E as we don't know the number of boxes being loaded in first 2 hours and last 2 hours
   1   2   3   4 
Moderators:
Math Expert
105356 posts
496 posts