Time and Work
MCQs Math


Question:     If Kenneth can finish the work in 42 days and Gregory can finish the same work in 46 days, then in how many days both can finish the work together?


Correct Answer  21 21/22 days or 21.955 days

Solution And Explanation

Solution

Given,

The number of days to finish the work by Kenneth = 42 days

And, the number of days to finish the same work by Gregory = 46 days

Thus, the number of days to finish the work by Kenneth and Gregory together = ?

Here,

∵ In 42 days the work done by Kenneth = 1

∴ In 1 day, the work done by Kenneth = 1/42 part

Similarly,

∵ In 46 days the work done by Gregory = 1

∴ In 1 day, the work done by Gregory = 1/46 part

Now, in 1 day, the work done by Kenneth and Gregory together

= In 1 day work done by Kenneth + In 1 day the work done by Gregory

= 1/42 + 1/46

= 23 + 21/966

= 44/966 part of work

= 44 ÷ 2/966 ÷ 2 part of work

= 22/483 part of work

This means, in 1 day, 22/483 part of the work is done by Kenneth and Gregory together.

Now, the number of days required to finish 22/483 part of work by Kenneth + Gregory working together = 1

∴ the number of days required to finish 1 work by Kenneth + Gregory together

= 1/22/483

= 1 × 483/22 = 483/22 days

= 21 21/22 days = or 21.955 days

Thus, Kenneth and Gregory working together will finish the work in 21 21/22 days = or 21.955 days Answer

Shortcut Trick to solve the problems based on time and work using formula

Case: If A can finish a work in a days, and B can finish the same work in b days,
then working together the number of days require to finish the work
= a × b/a + b days.

Here given,

The number of days required to finish the work by Kenneth = 42 days

And the number of days required to finish the same work by Gregory = 46 days

Thus, the number of days required to finish the work Kenneth and Gregory working together = ?

Here a = 42 days

And, b = 46 days

Thus, using formula a × b/a + b days

The number of days required to finish the work when Kenneth and Gregory working together

= 42 × 46/42 + 46 days

= 1932/88 days

= 1932 ÷ 4/88 ÷ 4 = 483/22 days

= 21 21/22 days or 21.955

Thus, Kenneth and Gregory together will finish the work in 21 21/22 days or 21.955 days Answer


Similar Questions

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(3) Steven can finish a work in 37 days. Andrew can finish the same work in 42 days while Joshua can finish the work in 47 days. How long will it take to finish it if they work together?

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(7) If Eric can finish the work in 71 days and Gerald can finish the same work in 76 days, then in how many days both can finish the work together?

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