Time and Work
MCQs Math


Question:     If Kenneth can finish the work in 45 days and Gregory can finish the same work in 50 days, then in how many days both can finish the work together?


Correct Answer  23 13/19 days or 23.684 days

Solution And Explanation

Solution

Given,

The number of days to finish the work by Kenneth = 45 days

And, the number of days to finish the same work by Gregory = 50 days

Thus, the number of days to finish the work by Kenneth and Gregory together = ?

Here,

∵ In 45 days the work done by Kenneth = 1

∴ In 1 day, the work done by Kenneth = 1/45 part

Similarly,

∵ In 50 days the work done by Gregory = 1

∴ In 1 day, the work done by Gregory = 1/50 part

Now, in 1 day, the work done by Kenneth and Gregory together

= In 1 day work done by Kenneth + In 1 day the work done by Gregory

= 1/45 + 1/50

= 10 + 9/450

= 19/450 part of work

This means in 1 day, 19/450 part of work is done by Kenneth and Gregory working together.

Now, the number of days required to finish 19/450 part of work by Kenneth + Gregory working together = 1

∴ the number of days required to finish 1 work by Kenneth + Gregory together

= 1/19/450

= 1 × 450/19 = 450/19 days

= 23 13/19 days = or 23.684 days

Thus, Kenneth and Gregory working together will finish the work in 23 13/19 days = or 23.684 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 Kenneth = 45 days

And the number of days required to finish the same work by Gregory = 50 days

Thus, the number of days required to finish the work Kenneth and Gregory working together = ?

Here a = 45 days

And, b = 50 days

Thus, using formula a × b/a + b days

The number of days required to finish the work when Kenneth and Gregory working together

= 45 × 50/45 + 50 days

= 2250/95 days

= 2250 ÷ 5/95 ÷ 5 = 450/19 days

= 23 13/19 days or 23.684

Thus, Kenneth and Gregory together will finish the work in 23 13/19 days or 23.684 days Answer


Similar Questions

(1) If A can do a piece of work in 2 days, B can do the same piece of work in 3 days, while C alone can do the same work in 4 days. Find the number of days to finish the work when they all will work together.

(2) If Kevin can finish the work in 44 days and Frank can finish the same work in 47 days, then in how many days both can finish the work together?

(3) Betty can finish a work in 30 days. Sandra can finish the same work in 35 days while Ashley can finish the work in 40 days. How long will it take to finish it if they work together?

(4) Raymond can finish a work in 97 days. Dennis can finish the same work in 102 days while Jerry can finish the work in 107 days. How long will it take to finish it if they work together?

(5) Jack can finish a work in 99 days. Jerry can finish the same work in 104 days while Tyler can finish the work in 109 days. How long will it take to finish it if they work together?

(6) If Emily can finish the work in 37 days and Justin can finish the same work in 40 days, then in how many days both can finish the work together?

(7) Patrick can finish a work in 95 days. Jack can finish the same work in 100 days while Dennis can finish the work in 105 days. How long will it take to finish it if they work together?

(8) If Amanda can finish the work in 45 days and Patrick can finish the same work in 49 days, then in how many days both can finish the work 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?

(10) Ashley can finish a work in 36 days. Emily can finish the same work in 41 days while Donna can finish the work in 46 days. How long will it take to finish it if they work together?


NCERT Solution and CBSE Notes for class twelve, eleventh, tenth, ninth, seventh, sixth, fifth, fourth and General Math for competitive Exams. ©