Source: Official Guide for the GMAT 13th Ed. Problem Solving; #131 Official Guide for the GMAT 2015 14th Ed. Problem Solving; #131

1

David has d books, which is 3

David has d books, which is 3 times as many as Jeff and 1/2 as many as Paula. How many books do the three of them have altogether, in terms of d?

2 Explanations

1

SONIKA VASANTH

David had 3 times as many as Jeff
How did we get 1/3rds for Jeff
and Paula can have 1d when David have half of it
I am bit confused. Please guide

Thanks in advance:)

Dec 8, 2016 • Comment

Cydney Seigerman, Magoosh Tutor

Hi Sonika :)

Good questions! We're describing the number of books for the three in terms of the number of books that David has, d.

Let's say that Jeff has j number of books. Since David has three times as many books as Jeff,

3j = d

Now, let's solve for j to describe the number of books Jeff has in terms of d:

3j = d
j = (1/3)d

We can check this is correct using actual values. Let's say that David has 12 books, which means that Jeff has 4 books:

j = (1/3)d
j = (1/3)*12
j = 4

Dec 9, 2016 • Reply

1

Gravatar Mike McGarry, Magoosh Tutor

Dec 28, 2013 • Comment

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