Arithmatical - Time and Work
DIRECTIONS : Problems based on time and work.
6. |
A tyre has punctures. The first puncture alone would have made the tyre flat in 9 minutes and the second alone would have done it in 6 minutes. If air leaks out at a constant rate, how long does it take both the punctures together to make it flat? |
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A. 1x1/2 minutes |
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B. 3x1/2 minutes |
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C. 3x3/5 minutes |
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D. 4x1/4 minutes |
Solution |
1 minute's work of both the punctures | = (1/9+1/6) |
= 5/18 |
So, both the punctures will make the tyre flat in | = 18/5 |
= 3x3/7 days. |
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7. |
10 women can complete a work in 7 days and 10 children take 14 days to complete the work. How many days will 5 women and 10 children take to complete the work? |
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A. 1 |
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B. 3 |
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C. 5 |
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D. 7 |
Solution |
1 woman's 1 day's work | = 1/70 |
1 child's 1 day's work | = 1/140. |
(5 women +10 children)'s 1 day's work | = (5/70+10/140) |
= (1/14+1/14) |
= 1/7. |
5 women + 10 children will complete the work in 7 days. |
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8. |
A does a work in 10 days and B does the same work in 15 days. In how many days they together will do the same work? |
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A. 5 days |
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B. 6 days |
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C. 8 days |
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D. 9 days |
Solution |
A's 1 day's work | = 1/10 |
and B's 1 day's work | = 1/15. |
(A+B)'s 1 day's work | = (1/10+1/15) |
= 1/6. |
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9. |
10 men and 15 women together can complete a work in 6 days. It takes 100 days for one man alone to complete the same work. How many days will be required for one woman alone to complete the same work? |
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A. 90 |
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B. 145 |
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C. 150 |
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D. 225 |
Solution |
1 man's 1 day's work | = 1/100. |
10 men + 15 women)'s 1 day's work | = 1/6 |
15 women's 1 day's work, | = (1/6-10/100) |
=(1/6-1/10) |
= 1/15. |
1 woman's 1 day's work | = 1/225. |
1 woman alone can complete the work in 225 days. |
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10. |
A takes twice as much time as B or thrice as much time to finish a piece of work. Working together, they can finish the work in 2 days, can do the work alone in |
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A. 4 days |
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B. 6 days |
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C. 12 days |
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D. 15 days |
Solution |
Suppose A,B and C take x,x/2 and x/3 hours respectively to finish the work. |
Then, | (1/x+2/x+3/x) |
= 1/2 |
<=> 6/x=1/2 |
<=> 12. |
So, B takes 6 hours to finish the work. |
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