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Q.) Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an aptitude test. Alastair scored exactly \(\frac{1}{2}\)of Darren’s score, whose score was \(\frac{1}{5}\)th more than Cook’s score. Eoin scored \(\frac{2}{5}\)th more than Cook and Darren’s score was \(\frac{3}{2}\) times that of Bell’s score. If the average score (arithmetic mean) of the group was 50, what was the range of the scores of the group?

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Re: Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an apti [#permalink]

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22 Jan 2017, 06:39

EgmatQuantExpert wrote:

Q.) Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an aptitude test. Alastair scored exactly \(\frac{1}{2}\)of Darren’s score, whose score was \(\frac{1}{5}\)th more than Cook’s score. Eoin scored \(\frac{2}{5}\)th more than Cook and Darren’s score was \(\frac{3}{2}\) times that of Bell’s score. If the average score (arithmetic mean) of the group was 50, what was the range of the scores of the group?

A. 25 B. 30 C. 35 D. 40 E. 50

IMO, the Answer is B..The explanation is as follows. Consider the scores of Alastair to be A, Bell to be B, Cook to be C,Darren to be D and Eoin to be E. Given:-

A=1/2D C=D-1/5 B=2/3D E=D+1/5

Since average is 50. Summing A,B,C,D and E and taking average gives us value of D to be sixty.

Hence the lowest value in the set =1/2D=30 Biggest value in the set=D+1/5=60.2 Hence range =60.2- 30=30.2..which is approximated to 30. Hence answer is Option B

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Q.) Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an aptitude test. Alastair scored exactly \(\frac{1}{2}\)of Darren’s score, whose score was \(\frac{1}{5}\)th more than Cook’s score. Eoin scored \(\frac{2}{5}\)th more than Cook and Darren’s score was \(\frac{3}{2}\) times that of Bell’s score. If the average score (arithmetic mean) of the group was 50, what was the range of the scores of the group?

A. 25 B. 30 C. 35 D. 40 E. 50

IMO, the Answer is B..The explanation is as follows. Consider the scores of Alastair to be A, Bell to be B, Cook to be C,Darren to be D and Eoin to be E. Given:-

A=1/2D C=D-1/5 B=2/3D E=D+1/5

Since average is 50. Summing A,B,C,D and E and taking average gives us value of D to be sixty.

Hence the lowest value in the set =1/2D=30 Biggest value in the set=D+1/5=60.2 Hence range =60.2- 30=30.2..which is approximated to 30. Hence answer is Option B

Hey,

There are two things, which I want to point out -

1. The final value of A, B, C, D and E are all integers. So we don't need to approximate anything.

2. Also, the relation between C and D and a few others are not written correctly. Let me take an example -

"Darren’s score, whose score was \(\frac{1}{5}\)th more than Cook’s score"

This line means - D = C + \(\frac{1}{5}\)*C D = \(\frac{6C}{5}\)

Similarly, check the other ratios once. I am sure you will figure out the minor errors.

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Re: Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an apti [#permalink]

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22 Jan 2017, 15:08

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Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an aptitude test. Alastair scored exactly \(\frac{1}{2}\)of Darren’s score, whose score was \(\frac{1}{5}\)th more than Cook’s score. Eoin scored \(\frac{2}{5}\)th more than Cook and Darren’s score was \(\frac{3}{2}\) times that of Bell’s score. If the average score (arithmetic mean) of the group was 50, what was the range of the scores of the group?

A. 25 B. 30 C. 35 D. 40 E. 50

the 5 scores form a progression: C-2/5, C-1/5, C, C+1/5, C+2/5 if C=50, then progression is 30, 40, 50, 60, 70 range=70-30=40 D

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o Range of the score = Highest score – Lowest Score

Working Out

1. Let Alastair’s score be \(x\)……….(1)

2. Darren’s Score

a. We know that, Alastair’s score = \(\frac{1}{2}\) * Darren’s Score b. So, Darren’s score \(= 2x\)………..(2)

3. Cook’s Score

a. Now, we know that Darren’s Score = Cook’s score +\(\frac{1}{5} *\) Cook’s score b. So, we can write \(2x =\frac{6}{5}\) * Cook’s score c. So, Cook’s score \(= \frac{5x}{3}\)………..(3)

4. Bell’s Score

a. We know that Darren’s Score \(= \frac{3}{2}\) * Bell’s score b. So, we can write \(2x = \frac{3}{2}\) * Bell’s score c. Bell’s score \(= \frac{4x}{3}\)……(4)

5. Eoin’s Score

a. We know that Eoin’s score = Cook’s score \(+ \frac{2}{5}\) * Cook’s score b. So, we can write Eoin’s score \(= \frac{7x}{3}\) ……….(5)

6. Also, sum of all the scores \(= 250\)

a. \(x + 2x + \frac{5x}{3} + \frac{4x}{3} + \frac{7x}{3} = 250\) b. \(x = 30\) c. Hence, the difference between the highest and the lowest score \(= \frac{7x}{3} – x = 70 – 30 = 40\)

So, the range of the scores of the group is \(40\).

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Re: Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an apti [#permalink]

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25 Feb 2017, 12:39

Not a hard question but lot's of computation involved. I don't see how this can be done carefully in 2 minutes. Just reading, understanding, and planning how to attack this question takes a solid minute. Then there is a good 2-3 minutes of math involved (5 equations, then combining them, then solving for the variable, then determining the range).

Would it be fair to say that the GMAT likely wouldn't have a question this math heavy? Or is there a shortcut? Would questions like this typically have a shortcut? How long did it take people to solve this?

Re: Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an apti [#permalink]

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05 Apr 2017, 17:18

EgmatQuantExpert wrote:

Q.) Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an aptitude test. Alastair scored exactly \(\frac{1}{2}\)of Darren’s score, whose score was \(\frac{1}{5}\)th more than Cook’s score. Eoin scored \(\frac{2}{5}\)th more than Cook and Darren’s score was \(\frac{3}{2}\) times that of Bell’s score. If the average score (arithmetic mean) of the group was 50, what was the range of the scores of the group?

This problem looks a lot worse than it is. Solved for C, used decimals instead of fractions, and ignored A and B until the end (b/c the way the question is written suggests C as jumping off point).

Stage I

A = \(\frac{1}{2}\)D

B = ??

C = ??

D = \(\frac{1}{5}\) more than C = 1.2C

E = \(\frac{2}{5}\) more than C = 1.4C ----- Stage II

2 of 5 variables are in terms of C. Add C itself, and that's 3 of 5.

A and B in terms of C? ----- A = \(\frac{1}{2}\)or .5D.

D = 1.2C.

1.2C x .5 = .6C ----- B is hardest.

D = 1.5B. D also = 1.2C

1.5B = 1.2C

B = \(\frac{1.2}{1.5}\)C = \(\frac{12}{15}\)C = \(\frac{4}{5}\)C = .8C --- Stage III --Now the list is

A = .6C B = .8C C = 1.0C D = 1.2C E = 1.4C

And now there's an evenly spaced set/progression where median = mean, so C = 50.

Largest - smallest = range. E is 1.5 x 50 = 70. A is .6 x 50 = 30.

Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an apti [#permalink]

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11 Apr 2017, 15:05

EgmatQuantExpert wrote:

Q.) Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an aptitude test. Alastair scored exactly \(\frac{1}{2}\)of Darren’s score, whose score was \(\frac{1}{5}\)th more than Cook’s score. Eoin scored \(\frac{2}{5}\)th more than Cook and Darren’s score was \(\frac{3}{2}\) times that of Bell’s score. If the average score (arithmetic mean) of the group was 50, what was the range of the scores of the group?

Re: Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an apti [#permalink]

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17 Aug 2017, 09:43

EgmatQuantExpert wrote:

Q.) Five friends Alastair, Bell, Cook, Darren and Eoin appeared in an aptitude test. Alastair scored exactly \(\frac{1}{2}\)of Darren’s score, whose score was \(\frac{1}{5}\)th more than Cook’s score. Eoin scored \(\frac{2}{5}\)th more than Cook and Darren’s score was \(\frac{3}{2}\) times that of Bell’s score. If the average score (arithmetic mean) of the group was 50, what was the range of the scores of the group?

A. 25 B. 30 C. 35 D. 40 E. 50

From the question; A=1/2D D=6/5C E=7/5C B=2/3D

Looking at the average (=50) and answer choices (25,30,35,40,40) it is clear that all the scores are multiples of 5.. Now D is also a multiple of 6... So, D can be 6*5=30 or 6*5*2=60...as average is 50 and D is better than A,B and C...60 seems better Assume D=60...We get E=70, B=40, A=30, C=50....and voila...the avg is 50... So, range is 70-30=40

We can also take E..which is a multiple of 7 and 5...so probably 35 or 70..as E is highest..it is greater than 50...So take 70 again we get D=60, B=40, A=30, C=50..

Testing the values comes with practice...and by scanning the information and answer choices..but it does wonders
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