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nikhilagrawal: Senior | Next Rank: 100 Posts; Posts: 81; Joined: Thu Jun 12, 2008 1:57 pm; Thanked: 1 times

ratios

by nikhilagrawal » Fri Jul 25, 2008 2:19 am

At a certain school, the ratio of the number of second graders to the number of fourth graders is 8 to 5, and the ratio of the number of first graders to the number of second graders is 3 to 4. If the ratio of the number of third graders to the number of fourth graders is 3 to 2, what is the ratio of the number of first graders to the number of third graders?

A. 16 to 15
B. 9 to 5
C. 5 to 16
D. 5 to 4
E. 4 to 5

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Source: Beat The GMAT — Problem Solving | Fri Jul 25, 2008 2:19 am

amitansu: Master | Next Rank: 500 Posts; Posts: 294; Joined: Tue Feb 26, 2008 9:05 pm; Thanked: 13 times; Followed by:1 members

by amitansu » Fri Jul 25, 2008 2:26 am

Ans is 'E' here.

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pepeprepa: Legendary Member; Posts: 661; Joined: Tue Jul 08, 2008 12:58 pm; Location: France; Thanked: 48 times

by pepeprepa » Fri Jul 25, 2008 5:53 am

ratio of first graders to second graders 3 to 4 (also 12 to 16)
ratio of second graders to fourth graders 8 to 5 (also 16 to 10)
ratio of third graders to fourth graders 3 to 2, so the ratio of fourth graders to third graders is 2 to 3 (also 10 to 15)

Therefore, we can write joining all these rartios: "12 to 16 to 10 to 15"

First graders to third graders: 12 to 15 which is 4 to 5

E

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sudhir3127: Legendary Member; Posts: 829; Joined: Mon Jul 07, 2008 10:09 pm; Location: INDIA; Thanked: 84 times; Followed by:3 members