Question

10 worker can construct a wall in 12 hours . How long will 8 workers take to construct the same wall..

Answer 1

10×12=8×h
h=10×12/8
h=15


$hence \: 8 \: workers \: construct \: the \: same \: wall \: in \: 15 \: hours$

Answer 2

The number of workers is inversely proportional to the number of hours needed.

⇒ The more workers we have, the fewer hours needed

⇒ The fewer workers we have, the more hours needed

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10 workers = 12 hours (Given)

Find the number of hours needed if there is only 1 worker:

10 workers = 12 hours

1 worker = 12 x 10 = 120 hours

Find the number of hours needed if there are 8 workers:

1 worker = 120 hours

8 workers = 120 ÷ 8 = 15 hours

Answer: 8 workers need 15 hours

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SHORTCUT:

Number of hours needed for 8 workers = (10 x 12)/8 = hours

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