Question

plz solve
When A and B work together then they take 4 hours to complete a piece of work. When B alone works at 75% of his efficiency then he takes 8 hours to complete half of the piece of work. Find the number of hours A alone will take to complete the piece of work if he works at 75% his efficiency?

Answer 1

Answer:

when B alone works at 75% of his efficiency he takes 8 hours to complete half of work therefore by the same efficiency A will complete the half work in 8 hours and if we want to find the full work completion then multiply half by 2

the answer is 16 hours which is the required answer

plz mark as brainliest

Answer 2

Given :

Time taken by A and B to complete work together = 4 hr

Time taken by B to complete half the work with 75% of his efficiency = 8 hr

To find :

Time taken by A to complete the work with 75% of his efficiency .

Solution :

Let time taken by A and B to complete the work alone with full efficiency be x and y respectively .

then , work done in 1 hr working together ,

(1/x) + (1/y) = (1/4)     ...........(i)

time taken by to complete half the work with 75% of his efficiency = 8 hr

for complete work , B will take 16 hours with 75% of his efficiency .

→ y * (100/75) = 16

→ y = 12 hrs

time taken by B to complete work alone with full efficiency = 12 hours .

by (i) ,

(1/x) + (1/12) = (1/4)

→ x = 6 hrs

time taken by A to complete work alone with 75% efficiency

= ( 6 ) * ( 100/75 )

= 8 hrs

A takes 8 hours to complete work alone with 75% efficiency .