RenB
Bunuel
There is a certain number of students in Mr. Stewart’s class. Could Mr. Stewart evenly divide the class into 3 study groups?
(1) If Mr. Stewart reduced the number of students in his class by 16 percent he could evenly divide the class into groups of 9.
(2) If Mr. Stewart reduced the number of students in his class by 6 percent he could evenly divide the class into groups of 3.
Hi
This is the logic that I applied:
Let the number of students be 100x. The qs asks me, is 100x divisible by 3. Its a yes/no data sufficiency problem.
St 1- Class size becomes 84x. 84x= 3*7*2*2*x is divisible by 9 (which has two 3s as its factor).
84 has only one 3. Definitely x has to have one 3 as its factor so that 84 x is divisible by 9. Hence sufficient that x is divisible by 3 thus 100x is
St 2- 94x is divisible by 3. 94 doesnt have 3 as its factor. Thus it must be true that x is divisible by 3 so that 94x is. Hence sufficient taht x is divisible by 3 and thus 100x is.
Bunuel chetan2u is this approach correct?
How could you assume that the number of students in the class is a multiple of 100? However, the overall logic is correct.
There is a certain number of students in Mr. Stewart’s class. Could Mr. Stewart evenly divide the class into 3 study groups?Let the number of students in the class be \(n\). The question essentially asks whether \(n\) is a multiple of 3.
(1) If Mr. Stewart reduced the number of students in his class by 16 percent he could evenly divide the class into groups of 9.
This statement implies that \(\frac{84}{100} * n = \frac{21}{25} * n = 3(\frac{7}{25} * n)\) is a multiple of 9. For \(3(\frac{7}{25} * n)\) to be a multiple of 9, \(n\) must be a multiple of 3. Sufficient.
(2) If Mr. Stewart reduced the number of students in his class by 6 percent he could evenly divide the class into groups of 3.
This statement implies that \(\frac{94}{100} * n = \frac{47}{50} * n\) is a multiple of 3. For \(\frac{47}{50} * n\) to be a multiple of 3, \(n\) must be a multiple of 3. Sufficient.
Answer: D.