Question 6 (nov. 15th)

[bacali]

Six machines, each working at the same constant rate, together can complete a certain job in 12 days. How many additional machines, each working at the same constant rate, will be needed to complete te job in 8 days?

A) 2
B) 3
C) 4
D) 6
E) 8

OA: B

[dmateer25]

https://www.beatthegmat.com/work-problem-t15889.html

[cramya]

6 machines takes 12 days to finish a job
1 machine will take 72 days

To finsih a job in 72 days 1 machine is needed
To finish a job in 8 days of of machines needed will be 72/8 = 9 machines

Differecne = 9-6 =3

3 additional machines needed

[canuckclint]

From the general formula:
6(1/x) = 1/12
Then for n more machines:
6/x + n/x = 1/8

Substitute:
1/12 + n/(12*6) = 1/8

n = 3