Hang Tuah wrote:

2 pumps working simultaneously at their respective rates took exactly 4 hours to fill a certain swimming pool. If the constant rate of one pump was 1.5 times the constant rate of the other, how many hours would it take for the faster pump to fill the pool if it had worked alone at its constant rate?

A. 5

B. 16/3

C. 11/2

D. 6

E. 20/3

This is what I did:

Step 1: 1/0.5x + 1/x = 1/4.

Step 2: Solve for x. I got x = 12.

Step 3: Hence the faster pump can complete the job in 6 hours (i.e. 0.5 of 12)

But the OA is E. Appreciate your help.

Thanks.

Your first equation was wrong.

1/0.5x + 1/x = 1/4.

I dont know where did u get 0.5 from?

The basic formula is

(1/r) + (1/s) = (1/h)

r and s are number of hours person 1 and person 2 needs working alone for a job and h is the number of hours it takes when they do the same job together

(1/r) = rate of working for first person for a job

(1/s) = rate of working for the second for a job

(1/h) = combined rate of working for a job.

Hope this helps you!