Question

Two persons A and B working together can dig a trench in 8 hours while A alone can dig it in 12
hours. In how many hours B alone can dig such a trench?
Select one:
O a. 27
O b. 24
O c. 25
O d. 29​

Answer 1

Answer:

B

Step-by-step explanation:

(A+B)'s one hour work=1/8 and A's hour day work=1/12

therefore B's one hour work=1/8-1/12=1/24

B takes 24 hours to complete the work

Answer 2

Answer:

Option (b )In 24 hours B alone can dig such a trench .

Step-by-step explanation:

Explanation:

Given , A and B working together can dig a trench in 8 hours

and  A alone can dig a trench in 12 hours .

Step1:

Time taken by A and B together = A+B = 8 hours

Work done by A and B together in 1 hour = $\frac{1}{8}$

Time taken by A alone = 12 hours

work done by A alone = $\frac{1}{12}$

Therefore , work done by B alone = $\frac{1}{8} - \frac{1}{12}$ = $\frac{3-2}{24} =\frac{1}{24}$

So, Time taken by B alone is 24 hours

Final answer :

Hence , time taken by B alone can dig a trench is 24 hours,

so the correct option is (b) which is 24 hours .