A company has two types of machines, type R and type S.
A company has two types of machines, type R and type S. Operating at a constant rate a machine of R does a certain job in 36 hours and a machine of type S does the job in 2 hours. If the company used the same number of each type of machine to do job in 12 hours,how many machine R were used?
Answer/Solution
18/19
Steps/Work
yes there is a typo in the question, I got the same ques on my GMAT PREP last week, and the questions goes as:
A company has two types of machines,type R and type S.Operating at a constant rate a machine of R does a certain job in 36 hours and a machine of type S does the job in 2 hours .If the company used the same number of each type of machine to do job in2 hours,how many machine R were used?
So for a job to be done in 2 hours R = 1/2
R_a(Rate of Machine R) = 1/36
R_s(Rate of Machine S) = 1/2
Lets say x machines are used to attain the desired rate, thus
x/36+x/2 = 1/2 (Desired R =1/2 i.e. to complete the job in 2 hours)
(x+18x)/36 = 1/2
19x/36 = 1/2
x = 18/19.
QA = 18/19 (ANSWER C)
A company has two types of machines,type R and type S.Operating at a constant rate a machine of R does a certain job in 36 hours and a machine of type S does the job in 2 hours .If the company used the same number of each type of machine to do job in2 hours,how many machine R were used?
So for a job to be done in 2 hours R = 1/2
R_a(Rate of Machine R) = 1/36
R_s(Rate of Machine S) = 1/2
Lets say x machines are used to attain the desired rate, thus
x/36+x/2 = 1/2 (Desired R =1/2 i.e. to complete the job in 2 hours)
(x+18x)/36 = 1/2
19x/36 = 1/2
x = 18/19.
QA = 18/19 (ANSWER C)