Question

5. A finished 3/10 of a work in 9 days for colouring of a house. A and B together completed rest work in 7 days. If B alone works, how many days he would have taken to complete the entire work?​

Answer 1

Answer:

Answer is 15

Step-by-step explanation:

Solution…

We know, A finished 3/10 of a work in 9 days.

A➡️ 3/10 × 9 Work/Day

A+B➡️ 7/10×7 Work/Day

B➡️ 7/10 — 3/90

7×9 — 3×7

63–21/630

42/630

630÷42 = 15 ans.,✓

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Answer 2

Given,

A finished 3/10 of a work in 9 days.

A and B together completed rest work in 7 days.

To find,

Number of required days for B to complete the entire work, alone.

Solution,

We can simply solve this mathematical problem by using the following mathematical process.

Let, the total amount of work = 1

So,

A alone finishes in 9 days = 3/10 part of work

A alone finishes in 1 day = (3/10) × (1/9) = 1/30 part of work

And,

After A works for 9 days, the remaining work = (1) - (3/10) = 7/10 part of work

So,

A and B together finishes in 7 days = 7/10 part of work

A and B together finishes in 1 day = (7/10) × (1/7) = 1/10 part of work

Now,

B alone finishes in 1 day = (Amount of work A and B together finishes in 1 day) - (Amount of work A alone finishes in 1 day) = (1/10) - (1/30) = (3-1)/30 = 2/30 = 1/15 part of work

So,

B alone can finish 1/15 part of work in = 1 day

B alone can finish 1 part of work in = 1 × (15/1) = 15 days

Hence, B alone can finish the entire work in 15 days.