Four paint brushes-A, B, C and D are used to paint or distort a sheet. A is twice as fast as B, C is twice as fast as D and B is 3/2 as fast as C. A distorts (1/8)th of the sheet, B distorts (1/4)th, C paints (3/8)th and D paints the rest. Only one paint brush can work at a time. It takes a total of 120 hours to paint the sheet. What is the time taken by C and D to paint the sheet?
Four paint brushes-A, B, C and D are used to paint or distort a sheet. A is twice as fast as B, C is twice as fast as D and B is 3/2 as fast as C. A distorts (1/8)th of the sheet, B distorts (1/4)th, C paints (3/8)th and D paints the rest. Only one paint brush can work at a time. It takes a total of 120 hours to paint the sheet. What is the time taken by C and D to paint the sheet? Correct Answer 540
Given:
A is twice as fast as B, C is twice as fast as D and B is 3/2 as fast as C.
Assumption:
Let the time taken by A, B, C and D to fill or distort the sheet be t, 2t, 3t and 6t respectively.
Calculation:
A distorts(1/8)th part of the sheet.
Time taken by A to paint= t × (1/8) = t/8
∴ Total time to paint the sheet = - (t/8) – (2t) (1/4) + (3t) (3/8) + (6t)(1/4)
⇒ 2t = 120 hours
⇒ t = 60 hours
Now,
Time taken by C and D to paint the sheet= 3t + 6t = 9t = 540
∴ The time taken by C and D to paint the sheet is 540 hours.