Basic Maths Mcqs

8 children and 12 men complete a certain piece of work in 9 days. If each child takes twice the time taken by a man to finish the work, in how many days will 12 men finish the same work ?

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8 children and 12 men complete a certain piece of work in 9 days. If each child takes twice the time taken by a man to finish the work, in how many days will 12 men finish the same work ?

A. 6 days
B. 8 days
C. 10 days
D. 12 days
2 children = 1 man
(8 children + 12 men ) = 16 men
Now, less men, more days
12 : 16 : 9 : x
x = 16×9/12=12 days

15 men can build a 500m long wall in 30 days. In how many days can 30 men build a 1.2 km long wall?

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15 men can build a 500m long wall in 30 days. In how many days can 30 men build a 1.2 km long wall?

A. 48 days
B. 24 days
C. 40 days
D. 36 days
No. of days is
directly proportional to the length of the wall and
inversely proportional to the number of men No. of days = (1200/500)*(15/30)*30 = 36 days

If 28 men can finish a work in 15 days, 21 men can finish the same work in___________?

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If 28 men can finish a work in 15 days, 21 men can finish the same work in___________?

A. 24 days
B. 14 days
C. 15 days
D. 20 days
Time and Men are inversely proportional. Time taken by 28 men to finish the work = 15 days Time taken by a man to finish the work
= 15*28 days Time taken by 21 men = (15*28)/21 = 20 days

C takes 6 days to complete half of a work and D takes 5 days to complete 1/3rd of the same work. They take turns to complete the task. If C works for the first 4 days, in how many days will D complete the rest of the work without the help of C?

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C takes 6 days to complete half of a work and D takes 5 days to complete 1/3rd of the same work. They take turns to complete the task. If C works for the first 4 days, in how many days will D complete the rest of the work without the help of C?

A. 10 days
B. 12 days
C. 8 days
D. 9 days
Part of work completed by C in 1 day = 1/12 Part of work completed by D in 1 day = 1/15 Part of work completed by C in 4 days
= 1/3 Work remaining = 2/3 Time taken by D to complete the work
= (2/3)÷(1/15) = 10 days

P,Q and R together earn Rs.1620 in 9 days. P and R can earn Rs.600 in 5 days. Q and R in 7 days can earn Rs.910. How much amount does R can earn per day?

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P,Q and R together earn Rs.1620 in 9 days. P and R can earn Rs.600 in 5 days. Q and R in 7 days can earn Rs.910. How much amount does R can earn per day?

A. Rs.40
B. Rs.70
C. Rs.90
D. Rs.100
Amount Earned by P,Q and R in 1 day = 1620/9 = 180 —(1)
Amount Earned by P and R in 1 day = 600/5 = 120 —(2)
Amount Earned by Q and R in 1 day = 910/7 = 130 —(3)
(2)+(3)-(1) => Amount Earned by P , Q and 2R in 1 day
– Amount Earned by P,Q and R in 1 day = 120+130-180 = 70
=>Amount Earned by R in 1 day = 70

P and Q can complete a work in 20 days and 12 days respectively. P alone started the work and Q joined him after 4 days till the completion of the work. How long did the work last?

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P and Q can complete a work in 20 days and 12 days respectively. P alone started the work and Q joined him after 4 days till the completion of the work. How long did the work last?

A. 5 days
B. 10 days
C. 15 days
D. 12 days
Work done by P in 1 day = 1/20
Work done by Q in 1 day = 1/12
Work done by P in 4 days = 4 × (1/20) = 1/5
Remaining work = 1 – 1/5 = 4/5
Work done by P and Q in 1 day = 1/20 + 1/12 = 8/60 = 2/15
Number of days P and Q take to complete the remaining work = (4/5) / (2/15) = 6
Total days = 4 + 6 = 10

P can finish a work in 18 days. Q can finish the same work in 15 days. Q worked for 10 days and left the job. how many days does P alone need to finish the remaining work?

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P can finish a work in 18 days. Q can finish the same work in 15 days. Q worked for 10 days and left the job. how many days does P alone need to finish the remaining work?

A. 8
B. 6
C. 4
D. 2
Work done by P in 1 day = 1/18
Work done by Q in 1 day = 1/15
Work done by Q in 10 days = 10/15 = 2/3
Remaining work = 1 – 2/3 = 1/3
Number of days in which P can finish the remaining work = (1/3) / (1/18) = 6

P can lay railway track between two stations in 16 days. Q can do the same job in 12 days. With the help of R, they completes the job in 4 days. How much days does it take for R alone to complete the work?

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P can lay railway track between two stations in 16 days. Q can do the same job in 12 days. With the help of R, they completes the job in 4 days. How much days does it take for R alone to complete the work?

A. 9(3/5) days
B. 9(1/5) days
C. 9(2/5) days
D. 10 days
Amount of work P can do in 1 day = 1/16
Amount of work Q can do in 1 day = 1/12
Amount of work P, Q and R can together do in 1 day = 1/4
Amount of work R can do in 1 day = 1/4 – (1/16 + 1/12) = 3/16 – 1/12 = 5/48
=> Hence R can do the job on 48/5 days = 9 (3/5) days

wo pipes X and Y fill a tank in 15 hrs. and 20 hrs. respectively, while a third pipe ‘Z’ can empty the full tank in 25 hrs.  All the three pipes are opened in the beginning.  After 10 hrs. Z is closed.  In how much time, will the tank be full ?

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wo pipes X and Y fill a tank in 15 hrs. and 20 hrs. respectively, while a third pipe ‘Z’ can empty the full tank in 25 hrs.  All the three pipes are opened in the beginning.  After 10 hrs. Z is closed.  In how much time, will the tank be full ?

A. 12 hrs
B. 14 hrs
C. 16 hrs
D. 18 hrs
Explanation:
Part filled in 10 hrs.
= 10[1/15+1/20−1/25]=23/30