Events & Promotions
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Apr 2308:00 PM PDT
-09:00 PM PDT
Video explanations + diagnosis of 10 weakest areas + 150+ short videos + study plan!
Apr 2301:30 AM EDT
-02:30 AM EDT
Struggling with GMAT Verbal as a non-native speaker? Harsh improved his score from 595 to 695 in just 45 days—and scored a 99 %ile in Verbal (V88)! Learn how smart strategy, clarity, and guided prep helped him gain 100 points.
Apr 2512:30 AM EDT
-01:30 AM EDT
At one point, she believed GMAT wasn’t for her. After scoring 595, self-doubt crept in and she questioned her potential. But instead of quitting, she made the right strategic changes. The result? A remarkable comeback to 695. Check out how Saakshi did it.
Apr 2610:00 AM EDT
-11:00 AM EDT
The Target Test Prep course represents a quantum leap forward in GMAT preparation, a radical reinterpretation of the way that students should study. Try before you buy with a 5-day, full-access trial of the course for FREE!
Apr 2711:00 AM EDT
-12:00 PM EDT
Prefer video-based learning? The Target Test Prep OnDemand course is a one-of-a-kind video masterclass featuring 400 hours of lecture-style teaching by Scott Woodbury-Stewart, founder of Target Test Prep and one of the most accomplished GMAT instructors
Apr 2808:00 AM PDT
-11:00 AM PDT
Whether you are just beginning your MBA journey or fine-tuning your path to a 700+ score, GMAT Day is designed to give you a competitive edge.
09 Dec 2021, 04:15
Kudos
Bookmarks
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
95%
(hard)
Question Stats:
59% (03:43) correct
41%
(03:30)
wrong
based on 157
sessions
History
Date
Time
Result
Not Attempted Yet
5 scores in a classroom are broken into 5 different ranges: 51-60, 61-70, 71-80, 81-90 and 91-100. The number of students who have scored in each range is given below. Furthermore, we know that the number of students who scored 76 or more is at least one more than those who scored below 75. What is the minimum possible average overall of this class?
51 to 60 - 3 students
61 to 70 - 8 students
71 to 80 - 7 students
81 to 90 - 4 students
91 to 100 - 3 students
A. 72
B. 71.2
C. 70.6
D. 69.2
E. 75
Are You Up For the Challenge: 700 Level Questions
51 to 60 - 3 students
61 to 70 - 8 students
71 to 80 - 7 students
81 to 90 - 4 students
91 to 100 - 3 students
A. 72
B. 71.2
C. 70.6
D. 69.2
E. 75
Are You Up For the Challenge: 700 Level Questions
10 Dec 2021, 00:23
Kudos
Bookmarks
I took the (minimum of each range and multiplied it by number of students) / total students :
(3∗51)+(8∗61)+71+(6∗76)+(4∗81)+(3∗91) / total students =25 , and got the answer as 70.5. Is this right?
(3∗51)+(8∗61)+71+(6∗76)+(4∗81)+(3∗91) / total students =25 , and got the answer as 70.5. Is this right?
10 Dec 2021, 02:19
Kudos
Bookmarks
Suggestion: To approach any optimization (maximize or minimize anything) problem, it is ideal to take first step as identification of varying parts and fixed parts.
In the given question,
1. Students in each range of scores.
2. "we know that the number of students who scored 76 or more is at least one more than those who scored below 75"
From above two points, we can see that, to minimize the average (or in other words, minimize the "total score" [Why? Because the number of students are fixed and hence the denominator in average is fixed, refer to start of this comment - Identify the moving and static parts!] apart from the students who scored in range 71-80, we can take minimum score for rest of the ranges and hence,
(3 * 51) + (8 * 61) + (4 * 81) + (3 * 91) -- We'll keep this sum as is for now and not touch it till the end. [Let's call it S]
Now our next target would be to identify how do we split the number of students such that condition (1) and (2) are satisfied.
If we consider the following,
The number of students who scored between 71-75 are x
The number of students who scored between 76-80 are y
Then we can say, x + y = 7 (Because total number of students who scored in 71 - 80 are 7)
And from statement (2) mentioned above, we can say that
= (4 + 3 + y) >= (x + 3 + 8) + 1
[Expanding: People who scored 76 or more >= (People who scored below 75) + 1]
= 7+y >= x+12
Using (From x+y = 7 => y = 7-x)
= 14 - 12 >= 2x
= x <= 1
Since, we want smaller number to contribute in our total sum, if we put x = 0 then y = 7, the sum contributed from range (71-80) will be 76 * 7 [Ah also, why 76? Because question restricts us to do so! The range is split now, 71-75 and 76-80] which is definitely more than if we take x = 1 (i.e. 1 student scored in range 71-75) in which case y = 6 (i.e. 6 students scored between 76 - 80).
So finally, answer would be
(S + 71*1 + 76*6) / 25
which is equal to 70.6 and hence option (C)
In the given question,
1. Students in each range of scores.
2. "we know that the number of students who scored 76 or more is at least one more than those who scored below 75"
From above two points, we can see that, to minimize the average (or in other words, minimize the "total score" [Why? Because the number of students are fixed and hence the denominator in average is fixed, refer to start of this comment - Identify the moving and static parts!] apart from the students who scored in range 71-80, we can take minimum score for rest of the ranges and hence,
(3 * 51) + (8 * 61) + (4 * 81) + (3 * 91) -- We'll keep this sum as is for now and not touch it till the end. [Let's call it S]
Now our next target would be to identify how do we split the number of students such that condition (1) and (2) are satisfied.
If we consider the following,
The number of students who scored between 71-75 are x
The number of students who scored between 76-80 are y
Then we can say, x + y = 7 (Because total number of students who scored in 71 - 80 are 7)
And from statement (2) mentioned above, we can say that
= (4 + 3 + y) >= (x + 3 + 8) + 1
[Expanding: People who scored 76 or more >= (People who scored below 75) + 1]
= 7+y >= x+12
Using (From x+y = 7 => y = 7-x)
= 14 - 12 >= 2x
= x <= 1
Since, we want smaller number to contribute in our total sum, if we put x = 0 then y = 7, the sum contributed from range (71-80) will be 76 * 7 [Ah also, why 76? Because question restricts us to do so! The range is split now, 71-75 and 76-80] which is definitely more than if we take x = 1 (i.e. 1 student scored in range 71-75) in which case y = 6 (i.e. 6 students scored between 76 - 80).
So finally, answer would be
(S + 71*1 + 76*6) / 25
which is equal to 70.6 and hence option (C)
