Math questions from any Manhattan Prep GMAT Computer Adaptive Test.
kadeneclarke
Students
 
Posts: 6
Joined: Wed Dec 31, 1969 8:00 pm
 

CAT Exam 4 - Jim and Tom Jacket

by kadeneclarke Sun Jun 26, 2011 10:37 pm

I do not understand why my approach to the following CAT question is incorrect:-

If Jim earns x dollars per hour, it will take him 4 hours to earn exactly enough money to purchase a particular jacket. If Tom earns y dollars per hour, it will take him exactly 5 hours to earn enough money to purchase the same jacket. How much does the jacket cost?

(1) Tom makes 20% less per hour than Jim does.

(2) x + y = $43.75

SOLN

Jacket Price = 4x = 5y

(1) x=0.8y =>4*0.8y = 5y. I then solved for y to determine 5y

(2) x = 43.75-y => 4(43.75-y) = 5y. Again I solved for y to determine the price of the jacket, 5y.

As such, I chose (d) for my answer. MGMAT's soln treated this as a rate question - not sure why- and the result was different from what I got. Can someone say why is my approach incorrect?
kadeneclarke
Students
 
Posts: 6
Joined: Wed Dec 31, 1969 8:00 pm
 

Re: CAT Exam 4 - Jim and Tom Jacket

by kadeneclarke Tue Jun 28, 2011 4:38 am

Sorry, made a bobo on this one. 5y=4x=Price of Jacket but based on (1) 5*0.8x is the same as 4x so (1) alone is not sufficient. Just the kinda mistake I don't need..aaah!
jnelson0612
ManhattanGMAT Staff
 
Posts: 2664
Joined: Fri Feb 05, 2010 10:57 am
 

Re: CAT Exam 4 - Jim and Tom Jacket

by jnelson0612 Sat Jul 02, 2011 10:40 pm

Glad you figured it out!
Jamie Nelson
ManhattanGMAT Instructor