Time and Work
MCQs Math


Question:     If A can finish a work in 10 days and B can finish the same work in 15 days, then in how many days they both can finish the work working together?


Correct Answer  6 days

Solution And Explanation

Solution

Given,

The number of days to finish the work by A = 10 days

And, the number of days to finish the same work by B = 15 days

Thus, the number of days to finish the work by A and B working together = ?

Here, ∵ In 10 days the work done by A = 1

∴ In 1 day, the work done by A = 1/10

Similarly, ∵ In 15 days the work done by B = 1

∴ In 1 day, the work done by B = 1/15

Now, in 1 day, the work done by A and B together

= In 1 day work done by A + In 1 day the work done by B

= 1/10 + 1/15

= 3 + 2/30

= 5/30 6

= 1/6

This means in 1 day, 1/6 part of work is done by A and B working together.

Now, the number of days required to finish 1/6 work by A + B working together = 1

∴ the number of days required to finish 1 work by A + B working together

= 1/1/6

= 1 × 6/1 days= 6 days

Thus, A and B working together will finish the work in 6 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 to finish the work by A = 10 days

And, the number of days to finish the same work by B = 15 days

Thus, the number of days to finish the work by A and B working together = ?

Here "a" = 10 days

And, "b" = 15 days

Thus, using formula a × b/a + b days

The number of days reqire to finish the work when they work together

= 10 × 15/10 + 15

= 150/25 = 6

Thus, while working A and B together the number of days require to finish the work = 6 days Answer


Similar Questions

(1) If Nancy can finish the work in 25 days and Ronald can finish the same work in 29 days, then in how many days both can finish the work together?

(2) If Nicholas can finish the work in 69 days and Roger can finish the same work in 74 days, then in how many days both can finish the work together?

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(6) Benjamin can finish a work in 85 days. Gregory can finish the same work in 90 days while Alexander can finish the work in 95 days. How long will it take to finish it if they work together?

(7) If Dorothy can finish the work in 47 days and Jack can finish the same work in 51 days, then in how many days both can finish the work together?

(8) If Andrew can finish the work in 38 days and Scott can finish the same work in 42 days, then in how many days both can finish the work together?

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