Time and Work
MCQs Math


Question:     If Brenda can finish the work in 76 days and Arthur can finish the same work in 81 days, then in how many days both can finish the work together?


Correct Answer  39 33/157 days or 39.21 days

Solution And Explanation

Solution

Given,

The number of days to finish the work by Brenda = 76 days

And, the number of days to finish the same work by Arthur = 81 days

Thus, the number of days to finish the work by Brenda and Arthur together = ?

Here,

∵ In 76 days the work done by Brenda = 1

∴ In 1 day, the work done by Brenda = 1/76 part

Similarly,

∵ In 81 days the work done by Arthur = 1

∴ In 1 day, the work done by Arthur = 1/81 part

Now, in 1 day, the work done by Brenda and Arthur together

= In 1 day work done by Brenda + In 1 day the work done by Arthur

= 1/76 + 1/81

= 81 + 76/6156

= 157/6156 part of work

This means in 1 day, 157/6156 part of work is done by Brenda and Arthur working together.

Now, the number of days required to finish 157/6156 part of work by Brenda + Arthur working together = 1

∴ the number of days required to finish 1 work by Brenda + Arthur together

= 1/157/6156

= 1 × 6156/157 = 6156/157 days

= 39 33/157 days = or 39.21 days

Thus, Brenda and Arthur working together will finish the work in 39 33/157 days = or 39.21 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 Brenda = 76 days

And the number of days required to finish the same work by Arthur = 81 days

Thus, the number of days required to finish the work Brenda and Arthur working together = ?

Here a = 76 days

And, b = 81 days

Thus, using formula a × b/a + b days

The number of days required to finish the work when Brenda and Arthur working together

= 76 × 81/76 + 81 days

= 6156/157 days

= 39 33/157 days or 39.21

Thus, Brenda and Arthur together will finish the work in 39 33/157 days or 39.21 days Answer


Similar Questions

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(2) Brandon can finish a work in 83 days. Samuel can finish the same work in 88 days while Gregory can finish the work in 93 days. How long will it take to finish it if they work together?

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(6) If Patricia can finish the work in 5 days and William can finish the same work in 9 days, then in how many days both can finish the work together?

(7) If Lisa can finish the work in 23 days and George can finish the same work in 26 days, then in how many days both can finish the work together?

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(9) If Stephanie can finish the work in 56 days and Adam can finish the same work in 61 days, then in how many days both can finish the work together?

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