Question

If 15 workers can build a wall in 48 hours, how many workers will be needed to do the same work in 30 hours? If the number of workers is reduced by 6 then how much time will be needed to complete
the work.​

Answer 1

Answer:

24 workers

80 hours

Step-by-step explanation:

15 workers = 48 hours

Find the number of workers needed to complete the work in 1 hour:

15 x 48 workers = 48 ÷ 48 hours

720 workers = 1 hour

Find the number of workers needed to complete the work in 30 hour:

720 ÷ 30 workers = 1 x 30 hours

24 workers = 30 hour

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15 workers = 48 hours

⇒ The number of workers is reduced by 6

⇒ number of workers = 15 - 6 = 9

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

15 ÷ 15 workers = 48 x 15 hours

1 worker = 720 hours

Find the number of hours needed if there were only 9 worker:

1 x 9 worker = 720 ÷ 9 hours

9 workers = 80 hours

Answer 2

24 workers

48 hours / 80 hours

Step-by-step explanation:

(x) workers hours(y)

15 48

x 30

The no. of workers and time taken to do the work is in inverse variation.

k = 15×48

k = 720

x × y = k

x × 30 = 720

x = 720÷30

x = 24 workers

Therefore if the workers are reduced by 6

no.of workers will be 24-6

=15

no.of hours is 48

if workers are reduce from 15

then no.of workers is 9

workers hours

15 48

9 y

=15 × 48

=720

9 × y = 720

y = 720 ÷ 9

= 80 hours

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