1.

A and B can do a piece of work in 24 and 30 days respectively. Both started the work and worked for 6 days. Then B leaves the work and C joins and the remaining work is completed by A and C together in 11 days. Find the days in which C alone can do the work

Answer»

80
100
120
130

Solution :A's 1 day work = 1/24
B's 1 day work `= 1/30`
`(A+B)'s6` day work `= 9/20`
Remaining work `= 11/20`
it is done by A & C in 11 days.
`therefore 11 xx (1/24 + 1/C) = 11/20`
`RARR 1/24 + 1/C = 1/20`
`rArr 1/C = 1 /120`
`rArr C` can do work in 120 days.


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