Correct option is D
Given:
A can do 20% of the work in 4 days.
B can do
3331% of the work in 10 days.
A and B worked together for 9 days.
C completed the remaining work in 6 days.
Concept Used:
The work rate is expressed as the fraction of the work completed per day.
Solution:
Work done per day by A:
Work rate of A=420%=201 of the work per day
Work done per day by B: \text{Work rate of B} =
1031=301 of the work per day
Work rate of A and B together=201+301Work rate of A and B together=603+602=605=121Work done in 9 days=9×121=129=43=75% So, A and B together completed 75% of the work in 9 days.
C completed the remaining 25% of the work in 6 days.
Work rate of C=625%=241 of the work per dayWork rate of B and C together=301+241Work rate of B and C together=1204+1205=1209=403 of the work per day
Time required to complete 75% of the work:
Time required=40375%=10075×340=43×340=10 days Alternate Method:
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