Question

Man can do a piece of work in 7 days his son and man together can do it in 3 days how many days will the son take to complete the whole work

Answer 1

Answer:

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1st one & 2nd one can complete a work in 24 days and 36 days respectively

1st son 1 day work = 1/24

2nd son 1 day work = 1/36

man could alone complete the whole work in 36/11 days

=> Man 1 Day work  = 11/36

The man can do double work in same time

=> 3rd son 1 Day work = 11/72

All three son 1 day work  = 1/24 + 1/36 + 11/72

= (3 + 2 + 11)/72

= 16/72

= 2/9

all his sons together can complete the work in 9/2 Days

= 4.5 Days

Answer 2

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1st one & 2nd one can complete a work in 24 days and 36 days respectively

1st son 1 day work = 1/24

2nd son 1 day work = 1/36

man could alone complete the whole work in 36/11 days

=> Man 1 Day work = 11/36

The man can do double work in same time

=> 3rd son 1 Day work = 11/72

All three son 1 day work = 1/24 + 1/36 + 11/72

= (3 + 2 + 11)/72

= 16/72

= 2/9

all his sons together can complete the work in 9/2 Days

= 4.5 Days