Maggie is 15 years older than Bobby. How old is Bobby?

Question

(1) In 3 years, Maggie’s age will be 50% larger than Bobby’s age.
(2) Years ago, when Maggie was 25 years old, Bobby was 10 years old.

tripathymadhu31 · Accepted Answer

Ans- A

Given: M= B+15 - eq 1

(1) SUFFICIENT- 
 M+3= 1.5(B+3) - eq 2
Solving 1 & 2 we can find the values of M & B i.e., 42, 27 respectively.

(2) INSUFFICIENT
 years ago When M = 25, B = 10. It doesn' t give any additional information to find the age of M & B. It speaks the same as given. So Insufficient.

rdoshi · Answer

From question, if maggie's age is m and bobby's age is b, then
m = b + 15 ---- (a)

(1) m+3 = 1.5 (b+3) ---- (b)
From (a) & (b), we can calculate b. Therefore, this is SUFFICIENT.

(2) Let these ages be from x years ago.
Then, m-x = 25 and b-x = 10
=> m-b = 15 => m = b+15 ---- (c)
Since, (c) is same as (a). This is INSUFFICIENT.

Therefore, answer is A

Bunuel · Answer

MAGOOSH OFFICIAL SOLUTION:

Let M = Maggie’s age right now, and let B = Bobby’s age right now. The prompt gives us the equation M = B + 15.

Statement #1 gives us a second equation, (M + 3) = 1.5*(B + 3). Notice that I used a  multiplier for the percent increase . With this equation and the prompt equation, we have two equations with two unknowns, so we can solve for the values of M & B. We don’t need to perform those calculations: it is enough to know that we could. This statement, alone and by itself, is sufficient.

Statement #2 is already obvious from the prompt. If Maggie is 15 years older than Bobby, then when Maggie was 25, Bobby would have had to have been 10. There’s no surprise there. We are given absolutely no indication when these people were these ages, so this doesn’t help us at all. This statement, alone and by itself, is not sufficient.

Answer = (A)

Ekland · Answer

Yea that's MAgoosh explanation for sure. So essentially if 2 didnt repeat the stem then the answer might have been D.
The trap in this sort of question is to forget algebra the equation you formed in the question stem and quickly say sufficient for 2 since it makes it 2 equations 2 variables. Then you didnt realize it merely repeated the stem and if you solve it will lead to number equals number or variable equals variable or zero equals zero.. that sort of thing...

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Maggie is 15 years older than Bobby. How old is Bobby?

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