Time and Work
MCQs Math


Question:     Jonathan can finish a work in 73 days. Larry can finish the same work in 78 days while Justin can finish the work in 83 days. How long will it take to finish it if they work together?


Correct Answer  25 16927/18227 days or 25.929 days

Solution And Explanation

Solution

Given,

The number of days required to finish a piece of work by Jonathan = 73 days

And, the number of days required to finish the same work by Larry = 78 days

And, the number of days required to finish the same work by Justin = 83 days

Thus, the number of days required to finish the work by all of them if they work together = ?

Here,

∵ In 73 days the work is done by Jonathan = 1

∴ The work done by Jonathan in 1 day = 1/73

Similarly,

∵ In 78 days the work is done by Larry = 1

∴ The work done by Larry in 1 day = 1/78

Similarly,

∵ In 83 days the work is done by Justin = 1

∴ The work done by Justin in 1 day = 1/83 part

Now, the work done by Jonathan, Larry, and Justin together in 1 day

= Jonathan's 1 day work + Larry's 1 day work + Justin's 1 day work

= 1/73 + 1/78 + 1/83

= 6474 + 6059 + 5694/472602

= 18227/472602 part of work

This means in 1 day, 18227/472602 part of work is done by Jonathan, Larry and Justin working together.

Now, the number of days required to finish 18227/472602 part of work by Jonathan, Larry, and Justin working together = 1

∴ the number of days required to finish the whole work (1 work) by Jonathan + Larry + Justin together

= 1/18227/472602

= 1 × 472602/18227 = 472602/18227 days

= 25 16927/18227 days = or 25.929 days

Thus, Jonathan, Larry, and Justin working together will finish the total work (1 work) in 25 16927/18227 days = or 25.929 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, B can finish the same work in b days, and C can finish the work in c days
then working together the number of days required to finish the work
= a × b × c/ab + ac + bc days.

Here given,

The number of days required to finish the work by Jonathan = 73 days

And the number of days required to finish the same work by Larry = 78 days

And the number of days required to finish the work by Justin = 83 days

Thus, the number of days required to finish the work by Jonathan, Larry, and Justin together = ?

Here a = 73 days

And, b = 78 days

And, c = 83 days

Thus, using formula a × b × c/ab + ac + bc days

The number of days required to finish the work when Jonathan, Larry, and Justin working together

= 73 × 78 × 83/73 × 78 + 73 × 83 + 78 × 83 days

= 472602/5694 + 6059 + 6474 days

= 472602/18227 days

= 472602/18227 days

= 25 16927/18227 days or 25.929

Thus, Jonathan, Larry, and Justin together will finish the work in 25 16927/18227 days or 25.929 days Answer


Similar Questions

(1) Rebecca can finish a work in 58 days. Laura can finish the same work in 63 days while Cynthia can finish the work in 68 days. How long will it take to finish it if they work together?

(2) Gregory can finish a work in 89 days. Frank can finish the same work in 94 days while Patrick can finish the work in 99 days. How long will it take to finish it if they work together?

(3) If Mary can finish the work in 25 days and Michael can finish the same work in 41 days, then in how many days both can finish the work together?

(4) If Karen can finish the work in 21 days and Kevin can finish the same work in 24 days, then in how many days both can finish the work together?

(5) If Emma can finish the work in 80 days and Jordan can finish the same work in 85 days, then in how many days both can finish the work together?

(6) Jacob can finish a work in 65 days. Nicholas can finish the same work in 70 days while Eric can finish the work in 75 days. How long will it take to finish it if they work together?

(7) Margaret can finish a work in 28 days. Sandra can finish the same work in 29 days while Ashley can finish the work in 30 days. How long will it take to finish it if they work together?

(8) If Jason can finish the work in 59 days and Douglas can finish the same work in 64 days, then in how many days both can finish the work together?

(9) 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?

(10) If David can finish the work in 10 days and Christopher can finish the same work in 14 days, then in how many days both can finish the work together?


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