Time and Work
MCQs Math


Question:     If Barbara can finish the work in 35 days and Anthony can finish the same work in 51 days, then in how many days both can finish the work together?


Correct Answer  20 65/86 days or 20.756 days

Solution And Explanation

Solution

Given,

The number of days to finish the work by Barbara = 35 days

And, the number of days to finish the same work by Anthony = 51 days

Thus, the number of days to finish the work by Barbara and Anthony together = ?

Here,

∵ In 35 days the work done by Barbara = 1

∴ In 1 day, the work done by Barbara = 1/35 part

Similarly,

∵ In 51 days the work done by Anthony = 1

∴ In 1 day, the work done by Anthony = 1/51 part

Now, in 1 day, the work done by Barbara and Anthony together

= In 1 day work done by Barbara + In 1 day the work done by Anthony

= 1/35 + 1/51

= 51 + 35/1785

= 86/1785 part of work

This means in 1 day, 86/1785 part of work is done by Barbara and Anthony working together.

Now, the number of days required to finish 86/1785 part of work by Barbara + Anthony working together = 1

∴ the number of days required to finish 1 work by Barbara + Anthony together

= 1/86/1785

= 1 × 1785/86 = 1785/86 days

= 20 65/86 days = or 20.756 days

Thus, Barbara and Anthony working together will finish the work in 20 65/86 days = or 20.756 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 Barbara = 35 days

And the number of days required to finish the same work by Anthony = 51 days

Thus, the number of days required to finish the work Barbara and Anthony working together = ?

Here a = 35 days

And, b = 51 days

Thus, using formula a × b/a + b days

The number of days required to finish the work when Barbara and Anthony working together

= 35 × 51/35 + 51 days

= 1785/86 days

= 20 65/86 days or 20.756

Thus, Barbara and Anthony together will finish the work in 20 65/86 days or 20.756 days Answer


Similar Questions

(1) 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?

(2) Robert can finish a work in 7 days. Michael can finish the same work in 12 days while David can finish the work in 17 days. How long will it take to finish it if they work together?

(3) If Kenneth can finish the work in 42 days and Gregory can finish the same work in 45 days, then in how many days both can finish the work together?

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(6) 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?

(7) If Patricia can finish the work in 27 days and William can finish the same work in 43 days, then in how many days both can finish the work together?

(8) If Jack can finish a work in 8 days and Bill can finish the same work in 12 days, then in how many days they both can finish the work working together?

(9) If Annie can finish a work in 2 days and Bobby can finish the same work in 3 days, then in how many days they both can finish the work working together?

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