GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 15 Nov 2018, 13:26

### 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

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

## Events & Promotions

###### Events & Promotions in November
PrevNext
SuMoTuWeThFrSa
28293031123
45678910
11121314151617
18192021222324
2526272829301
Open Detailed Calendar
• ### Free GMAT Strategy Webinar

November 17, 2018

November 17, 2018

07:00 AM PST

09:00 AM PST

Nov. 17, 7 AM PST. Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.
• ### GMATbuster's Weekly GMAT Quant Quiz # 9

November 17, 2018

November 17, 2018

09:00 AM PST

11:00 AM PST

Join the Quiz Saturday November 17th, 9 AM PST. The Quiz will last approximately 2 hours. Make sure you are on time or you will be at a disadvantage.

# During a certain week, a seal ate 50 percent of the first 80 smelt it

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 50613
During a certain week, a seal ate 50 percent of the first 80 smelt it  [#permalink]

### Show Tags

12 Jul 2018, 00:14
00:00

Difficulty:

35% (medium)

Question Stats:

64% (02:15) correct 36% (01:45) wrong based on 45 sessions

### HideShow timer Statistics

During a certain week, a seal ate 50 percent of the first 80 smelt it came across, and 30 percent of the remaining smelt it came across. If the seal ate 40 percent of the smelt it came across during the entire week, how many smelt did it eat?

A. 24

B. 32

C. 55

D. 64

E. 80

_________________
MBA Section Director
Affiliations: GMATClub
Joined: 22 May 2017
Posts: 968
Concentration: Nonprofit
GPA: 4
WE: Engineering (Computer Software)
During a certain week, a seal ate 50 percent of the first 80 smelt it  [#permalink]

### Show Tags

Updated on: 12 Jul 2018, 05:07
A seal ate 50 percent of the first 80 smelt it came across => $$\frac{50}{100} * 80$$

Let x be the remaining number of smelt the seal came across

Total number is smelt the seal ate is $$\frac{50}{100} * 80 + \frac{30}{100} * x$$

=> $$\frac{50}{100} * 80 + \frac{30}{100} * x = \frac{40}{100} * (80 + x)$$

=> $$(50 * 80) + 30x = 40 * (80 + x)$$

=> $$4000 + 30x = 40x + 3200$$

=> $$10x = 4000 - 3200$$

=> $$x = 80$$

UPDATE :

At first I solved only for 'x' and chose option E but the question actually asks for the number of smelt the seal ate which is

$$\frac{50}{100}* 80 + \frac{30}{100}* 80 = 64$$

Hence option D Thanks EgmatQuantExpert for the correct solution

Important learning for me

After solving the variables, do explicitly check what the question has asked for. Don't just stop after calculating the variables you have assumed and pick an answer.
_________________

If you like my post press kudos +1

New project wSTAT(which Schools To Apply To?)

New - RC Butler - 2 RC's everyday

Originally posted by workout on 12 Jul 2018, 01:32.
Last edited by workout on 12 Jul 2018, 05:07, edited 4 times in total.
Director
Joined: 20 Feb 2015
Posts: 797
Concentration: Strategy, General Management
During a certain week, a seal ate 50 percent of the first 80 smelt it  [#permalink]

### Show Tags

Updated on: 12 Jul 2018, 05:55
Bunuel wrote:
During a certain week, a seal ate 50 percent of the first 80 smelt it came across, and 30 percent of the remaining smelt it came across. If the seal ate 40 percent of the smelt it came across during the entire week, how many smelt did it eat?

A. 24

B. 32

C. 55

D. 64

E. 80

let x+40 be the total no of smelts
50% of the first 80 smelt = 40
remaining = x
30% of the remaining =0.3x
it ate 40% of the total
0.4(x+40)=40+0.3x
0.4x+16=40+0.3x
0.1x=24
x=240
total no of smelts = 280
it ate 40% of 280
=112

help me out here !!

Corrected above !!

let x+40 be the total no of smelts
50% of the first 80 smelt = 40

remaining would be (x+40)-80=x-40
so the equation becomes
0.4(x+40)=40+0.3(x-40)
0.4x+16=40+0.3x-12
x=120

total no of smelts =120+40=160
it ate 40% of 160 = 64

D

Originally posted by CounterSniper on 12 Jul 2018, 04:04.
Last edited by CounterSniper on 12 Jul 2018, 05:55, edited 2 times in total.
MBA Section Director
Affiliations: GMATClub
Joined: 22 May 2017
Posts: 968
Concentration: Nonprofit
GPA: 4
WE: Engineering (Computer Software)
During a certain week, a seal ate 50 percent of the first 80 smelt it  [#permalink]

### Show Tags

12 Jul 2018, 04:28
1
CounterSniper wrote:
it ate 40% of the total
0.4(x+40)=40+0.3x

CounterSniper

it ate 40% of the total, so the equation becomes

0.4(x+80)=40+0.3x
_________________

If you like my post press kudos +1

New project wSTAT(which Schools To Apply To?)

New - RC Butler - 2 RC's everyday

MBA Section Director
Affiliations: GMATClub
Joined: 22 May 2017
Posts: 968
Concentration: Nonprofit
GPA: 4
WE: Engineering (Computer Software)
Re: During a certain week, a seal ate 50 percent of the first 80 smelt it  [#permalink]

### Show Tags

12 Jul 2018, 04:32
CounterSniper wrote:
let x+40 be the total no of smelts

Also, here the total number of smelts is x+80 not x+40
_________________

If you like my post press kudos +1

New project wSTAT(which Schools To Apply To?)

New - RC Butler - 2 RC's everyday

e-GMAT Representative
Joined: 04 Jan 2015
Posts: 2201
Re: During a certain week, a seal ate 50 percent of the first 80 smelt it  [#permalink]

### Show Tags

12 Jul 2018, 04:48
1
1

Solution

Given:

• In a certain week, a seal ate 50 percent of the first 80 smelt it came across.
• The seal ate 30% of remaining seal it came across.
• In total, seal ate 40 percent of the smelt it came across

To find:

• How many smelts did seal eat in the week?

Approach and Working:
Let us assume that seal came across x smelts after eating 50% of first 80 smelts it came across.
• 50% of 80+ 30% of x= 40% of (x+80)
• 40+0.3x= 0.4x+32
• x=80

Hence, seal ate 40+ 24= 64

Hence, the correct answer is option D.

_________________

Number Properties | Algebra |Quant Workshop

Success Stories
Guillermo's Success Story | Carrie's Success Story

Ace GMAT quant
Articles and Question to reach Q51 | Question of the week

Number Properties – Even Odd | LCM GCD | Statistics-1 | Statistics-2
Word Problems – Percentage 1 | Percentage 2 | Time and Work 1 | Time and Work 2 | Time, Speed and Distance 1 | Time, Speed and Distance 2
Advanced Topics- Permutation and Combination 1 | Permutation and Combination 2 | Permutation and Combination 3 | Probability
Geometry- Triangles 1 | Triangles 2 | Triangles 3 | Common Mistakes in Geometry
Algebra- Wavy line | Inequalities

Practice Questions
Number Properties 1 | Number Properties 2 | Algebra 1 | Geometry | Prime Numbers | Absolute value equations | Sets

| '4 out of Top 5' Instructors on gmatclub | 70 point improvement guarantee | www.e-gmat.com

e-GMAT Representative
Joined: 04 Jan 2015
Posts: 2201
Re: During a certain week, a seal ate 50 percent of the first 80 smelt it  [#permalink]

### Show Tags

12 Jul 2018, 04:50
Hey workout,

I think you found x but did not calculate the number of smelts the seat ate.

_________________

Number Properties | Algebra |Quant Workshop

Success Stories
Guillermo's Success Story | Carrie's Success Story

Ace GMAT quant
Articles and Question to reach Q51 | Question of the week

Number Properties – Even Odd | LCM GCD | Statistics-1 | Statistics-2
Word Problems – Percentage 1 | Percentage 2 | Time and Work 1 | Time and Work 2 | Time, Speed and Distance 1 | Time, Speed and Distance 2
Advanced Topics- Permutation and Combination 1 | Permutation and Combination 2 | Permutation and Combination 3 | Probability
Geometry- Triangles 1 | Triangles 2 | Triangles 3 | Common Mistakes in Geometry
Algebra- Wavy line | Inequalities

Practice Questions
Number Properties 1 | Number Properties 2 | Algebra 1 | Geometry | Prime Numbers | Absolute value equations | Sets

| '4 out of Top 5' Instructors on gmatclub | 70 point improvement guarantee | www.e-gmat.com

MBA Section Director
Affiliations: GMATClub
Joined: 22 May 2017
Posts: 968
Concentration: Nonprofit
GPA: 4
WE: Engineering (Computer Software)
Re: During a certain week, a seal ate 50 percent of the first 80 smelt it  [#permalink]

### Show Tags

12 Jul 2018, 04:54
workout wrote:
A seal ate 50 percent of the first 80 smelt it came across => $$\frac{50}{100} * 80$$

Let x be the remaining number of smelt the seal came across

Total number is smelt the seal ate is $$\frac{50}{100} * 80 + \frac{30}{100} * x$$

=> $$\frac{50}{100} * 80 + \frac{30}{100} * x = \frac{40}{100} * (80 + x)$$

=> $$(50 * 80) + 30x = 40 * (80 + x)$$

=> $$4000 + 30x = 40x + 3200$$

=> $$10x = 4000 - 3200$$

=> $$x = 80$$

Hence option E

It looks like I solved for the wrong thing. The question asks for the number of smelts the seal ate which is

$$\frac{50}{100}* 80 + \frac{30}{100}* 80 = 64$$

Hence option D Thanks EgmatQuantExpert for the correct solution
_________________

If you like my post press kudos +1

New project wSTAT(which Schools To Apply To?)

New - RC Butler - 2 RC's everyday

Director
Joined: 31 Oct 2013
Posts: 778
Concentration: Accounting, Finance
GPA: 3.68
WE: Analyst (Accounting)
During a certain week, a seal ate 50 percent of the first 80 smelt it  [#permalink]

### Show Tags

12 Jul 2018, 05:36
Bunuel wrote:
During a certain week, a seal ate 50 percent of the first 80 smelt it came across, and 30 percent of the remaining smelt it came across. If the seal ate 40 percent of the smelt it came across during the entire week, how many smelt did it eat?

A. 24

B. 32

C. 55

D. 64

E. 80

let assume the no. of smelt be x.

Case 1:

80*50% = 40

Case 2:

Remaining smelt :

(x -80)

So, the no. of smelt ate at second phase :

(x - 80)*30%

3(x - 80) / 10

Case 3: we can form an equation based on the information that seal ate a total of 40% smelt.

40 + 3(x -80) / 10 = x * 40%

(400 + 3x - 240) / 10 = 2x / 5

x = 160.

No of smelt ate : 40 + ( 160- 80) 30% = 40 + 24 = 64.

Thus the best answer is D.
During a certain week, a seal ate 50 percent of the first 80 smelt it &nbs [#permalink] 12 Jul 2018, 05:36
Display posts from previous: Sort by