Time and Work
MCQs Math


Question:     If John can finish the work in 9 days and Richard can finish the same work in 14 days, then in how many days both can finish the work together?


Correct Answer  5 11/23 days or 5.478 days

Solution And Explanation

Solution

Given,

The number of days to finish the work by John = 9 days

And, the number of days to finish the same work by Richard = 14 days

Thus, the number of days to finish the work by John and Richard together = ?

Here,

∵ In 9 days the work done by John = 1

∴ In 1 day, the work done by John = 1/9 part

Similarly,

∵ In 14 days the work done by Richard = 1

∴ In 1 day, the work done by Richard = 1/14 part

Now, in 1 day, the work done by John and Richard together

= In 1 day work done by John + In 1 day the work done by Richard

= 1/9 + 1/14

= 14 + 9/126

= 23/126 part of work

This means in 1 day, 23/126 part of work is done by John and Richard working together.

Now, the number of days required to finish 23/126 part of work by John + Richard working together = 1

∴ the number of days required to finish 1 work by John + Richard together

= 1/23/126

= 1 × 126/23 = 126/23 days

= 5 11/23 days = or 5.478 days

Thus, John and Richard working together will finish the work in 5 11/23 days = or 5.478 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 John = 9 days

And the number of days required to finish the same work by Richard = 14 days

Thus, the number of days required to finish the work John and Richard working together = ?

Here a = 9 days

And, b = 14 days

Thus, using formula a × b/a + b days

The number of days required to finish the work when John and Richard working together

= 9 × 14/9 + 14 days

= 126/23 days

= 5 11/23 days or 5.478

Thus, John and Richard together will finish the work in 5 11/23 days or 5.478 days Answer


Similar Questions

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