Question

A man and a boy can do a piece of work in 24 days. If the man works alone for last 4 days, it is complete in 5 days. How long would the boy take to do it alone ?​

Answer 1

(Man + boy)'s one day's work = 1/24

(Man + boy)'s 20 day's work = 20/24 = 5/6

Remaining 1/6 of the work is done by the man alone in 5 days, i.e., the man alone can do 1/30 of the work in 1 day.

∴ Boy's one day's work = 1/24 - 1/30 - 1/120

∴ Boy alone would take 120 days to complete the work.

Answer 2

Answer:

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(Man + boy)'s one days' work = 1/24

(Man + boy)'s 20 days' work = 20/24

= 5/6

Remaning 1/6 of the work is done by the man alone can do 1/30 of the work in 1 day.

Therefore Boy's one days' work

= 1/24 – 1/30

= 1/120

Therefore Boy would take 120 days to complete the work.