Time and Work
MCQs Math


Question:     If Justin can finish the work in 79 days and Jesse can finish the same work in 84 days, then in how many days both can finish the work together?


Correct Answer  40 116/163 days or 40.712 days

Solution And Explanation

Solution

Given,

The number of days to finish the work by Justin = 79 days

And, the number of days to finish the same work by Jesse = 84 days

Thus, the number of days to finish the work by Justin and Jesse together = ?

Here,

∵ In 79 days the work done by Justin = 1

∴ In 1 day, the work done by Justin = 1/79 part

Similarly,

∵ In 84 days the work done by Jesse = 1

∴ In 1 day, the work done by Jesse = 1/84 part

Now, in 1 day, the work done by Justin and Jesse together

= In 1 day work done by Justin + In 1 day the work done by Jesse

= 1/79 + 1/84

= 84 + 79/6636

= 163/6636 part of work

This means in 1 day, 163/6636 part of work is done by Justin and Jesse working together.

Now, the number of days required to finish 163/6636 part of work by Justin + Jesse working together = 1

∴ the number of days required to finish 1 work by Justin + Jesse together

= 1/163/6636

= 1 × 6636/163 = 6636/163 days

= 40 116/163 days = or 40.712 days

Thus, Justin and Jesse working together will finish the work in 40 116/163 days = or 40.712 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 Justin = 79 days

And the number of days required to finish the same work by Jesse = 84 days

Thus, the number of days required to finish the work Justin and Jesse working together = ?

Here a = 79 days

And, b = 84 days

Thus, using formula a × b/a + b days

The number of days required to finish the work when Justin and Jesse working together

= 79 × 84/79 + 84 days

= 6636/163 days

= 40 116/163 days or 40.712

Thus, Justin and Jesse together will finish the work in 40 116/163 days or 40.712 days Answer


Similar Questions

(1) If Alexander can finish the work in 91 days and Wayne can finish the same work in 96 days, then in how many days both can finish the work together?

(2) If David can finish the work in 32 days and Christopher can finish the same work in 48 days, then in how many days both can finish the work together?

(3) Melissa can finish a work in 52 days. Stephanie can finish the same work in 57 days while Rebecca can finish the work in 62 days. How long will it take to finish it if they work together?

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(5) If Thomas can finish the work in 21 days and Andrew can finish the same work in 26 days, then in how many days both can finish the work together?

(6) Eric can finish a work in 71 days. Stephen can finish the same work in 76 days while Larry can finish the work in 81 days. How long will it take to finish it if they work together?

(7) If Daniel can finish the work in 24 days and Timothy can finish the same work in 27 days, then in how many days both can finish the work together?

(8) Barbara can finish a work in 12 days. Susan can finish the same work in 13 days while Jessica can finish the work in 14 days. How long will it take to finish it if they work together?

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(10) If Robert can finish a work in 4 days and Bob can finish the same work in 6 days, then in how many days they both can finish the work working together?


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