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 Amanda can finish the work in 45 days and Patrick can finish the same work in 48 days, then in how many days both can finish the work together?

(2) Rachel can finish a work in 94 days. Janet can finish the same work in 99 days while Catherine can finish the work in 104 days. How long will it take to finish it if they work together?

(3) 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?

(4) If Robert can finish a work in 5 days and Bob can finish the same work in 6 days, then in how many days they both can finish the work working together?

(5) Jessica can finish a work in 16 days. Sarah can finish the same work in 17 days while Karen can finish the work in 18 days. How long will it take to finish it if they work together?

(6) David can finish a work in 9 days. William can finish the same work in 10 days while Richard can finish the work in 11 days. How long will it take to finish it if they work together?

(7) If Anthony can finish the work in 28 days and Jeffrey can finish the same work in 32 days, then in how many days both can finish the work together?

(8) 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?

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(10) If Ashley can finish the work in 33 days and Eric can finish the same work in 36 days, then in how many days both can finish the work together?


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