4. A can do a piece of work in 20 days while B can do it in 15 days. With the help of C, they finish
the work in 5 days. In what time would C alone do it?
Answers
Answer:
does in one day 1/20 part of the work.
B in one day does 1/15 part of the work.
A+ B together do in one day 1/20+1/15 part of the work= 7/60 part of the work.
A+B+ C do in one day 1/5 part of the work.
C alone does in one day 1/5–7/60 part of the work=[ 5/60 ]part of the work
Therefore C alone can do the work in 60/5 days= 12 days answer
Answer:
A can do the work in 20 days
⇒ 1 day = 1/20 of the work
B can do the work in 15 days
⇒ 1 day = 1/15 of the work
Find the amount of work A and B can complete in a day:
1 day = 1/20 + 1/15 = 7/60
Find the amount of work c can complete in a day:
a + b + c can complete the work in 5 days
⇒ 1 day = 1/5 of the work
C alone
⇒ 1 day = 1/5 - 7/60 = 1/12
Find number of days c needs to complete the work:
1/12 of the work = 1 day
12/12 of the work = 1 x 12 = 12 days
Answer: C can complete the work alone in 12 days.
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