Time and Work Mcqs

A and B together can complete a work in 1.2 days,. A alone can complete it in 20 days. If B does the work only for half a day daily, then in how many days A and B together will complete the work ?

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A and B together can complete a work in 1.2 days,. A alone can complete it in 20 days. If B does the work only for half a day daily, then in how many days A and B together will complete the work ?

A. 10 days
B. 11 days
C. 15 days
D. 20 days

X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4 days Y joined him till the completion of the work. How long did the work last ?

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X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4 days Y joined him till the completion of the work. How long did the work last ?

A. 6 days
B. 10 days
C. 15 days
D. 20 days
Work done by X in 4 days = ( 1/20X 4 ) = 1/5 Remaining work = (1 – 1/5 ) = 4/5 (X + Y)’s 1 day’s work = 1/20 + 1/12 = 8/60 = 2/15 Now, 2/15 work is done by X and Y in 1 day. So, 4/5 work will be done by X and Y in 15/2 X 4/5 = 6 days Hence, total time taken = (6 + 4) days = 10 days.

A and B can complete a work in 15 days and 10 days respectively. They started doing the work together but after 2 days B had to leave and A alone completed the remaining work. The whole work was completed in___________?

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A and B can complete a work in 15 days and 10 days respectively. They started doing the work together but after 2 days B had to leave and A alone completed the remaining work. The whole work was completed in___________?

A. 8 days
B. 10 days
C. 12 days
D. 15 days
(A.+ B)’s 1 day’s work = ( 1/15 + 1/10 ) = 1/6 Work done by A and B in 2 days = ( 1/6 X 2 ) = 1/3 Remaining work = ( 1 – 1/6 ) = 2/3
Now, 1/15 work is done by A in 1 day. so 2/3 work will be done by A in ( 15 X 2/3 ) = 10 days Hence, total time taken = (10 + 2) = 12 days.

A can do a certain work-in the same time in which B and C together can do it. If A and B together could do it in 10 days and C alone in 50 days, then B alone could do it in_________?

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A can do a certain work-in the same time in which B and C together can do it. If A and B together could do it in 10 days and C alone in 50 days, then B alone could do it in_________?

A. 15 days
B. 20 days
C. 25 days
D. 30 days
(A + B)’s 1 day’s work = 1/10; C’s 1 day’s work = 1/50 (A + B + C)’s 1 day’s work = 1/10 + 1/50 = 6/50 = 3/25 Also, A’s 1 day’s work = (B + C)’s 1 day’s work
From (i) and (ii), we get : 2 x (A’s 1 day’s work) = 3/25 As 1 day’s work = 3/50 B’s 1 day’s work = 1/10 – 3/50 = 2/50 = 1/25 So, B alone could do the work in 25 days.

A and B can do a work in 8 days, 13, and C can do the same work in 12 days. A, B and C together can finish it in 6 days. A and C together will do it in_________?

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A and B can do a work in 8 days, 13, and C can do the same work in 12 days. A, B and C together can finish it in 6 days. A and C together will do it in_________?

A. 4 days
B. 6 days
C. 8 days
D. 12 days
(A + B + C)’s 1 day’s work = 1/6; (A + B)’s 1 day’s work = 1/8 (B + C)’s 1 day’s work = 1/12 (A + C)’s 1 day’s work = ( 2 X 1/6 ) – ( 1/8 + 1/12 ) = ( 1/3 – 5/24 ) = 3/24 = 1/8 So, A and C together will do the woirk in 8 days.