Hi rommysingh,
This question has a slight 'bias' in it that leaves it slightly open to interpretation, which I'll get to in a moment.
From the prompt, we're given 2 rates:
1) JIM: (4 hours)(X dollars per hour) = 4X = ENOUGH money to purchase a jacket.
2) TOM: (5 hours)(Y dollars per hour) = 5Y = ENOUGH money to purchase the same jacket.
I believe that the original author of this question wants us to assume that the cost of the jacket is 4X (which is the same as 5Y). Stating that 4X is ENOUGH money to buy the jacket could be interpreted as meaning "the jacket costs 4X OR LESS"). I'm going to assume that the jacked DOES cost 4X (= 5Y).
Knowing that 4X = 5Y gives us a relationship between the two variables (which means that we might have a 'system' of equations; we might also be able to TEST VALUES). We're asked for the price of the jacket.
Fact 1: Tom makes 20% less per hour than Jim does.
This Fact is redundant information, but even if you don't realize that, by TESTING VALUES, you can prove that it leads to an infinite number of possible jacket prices....
IF....
X = 5
Y = 4
Then the price of the jacket is $20
IF....
X = 10
Y = 8
Then the price of the jacket is $40
IF....
X = 15
Y = 12
Then the price of the jacket is $60
Etc.
Fact 1 is INSUFFICIENT
Fact 2: X + Y = $43.75
This Fact gives us a second equation to work with (the first equation was 4X = 5Y). With 2 variables and 2 unique equations, we CAN solve for X and Y. Knowing that, we don't actually have to do the work - we could figure out the price of the jacket though.
If you're curious, here's one way that you could do the math using the 2 equations...
X = 43.75 - Y
4X = 5Y
4(43.75 - Y) = 5Y
175 - 4Y = 5Y
175 = 9Y
175/9 = Y
Thus, 5Y = 5(175/9)
Fact 2 is SUFFICIENT
Final Answer: B
GMAT assassins aren't born, they're made,
Rich
