Time and Work
MCQs Math


Question:     Deborah can finish a work in 50 days. Stephanie can finish the same work in 51 days while Rebecca can finish the work in 52 days. How long will it take to finish it if they work together?


Correct Answer  16 3884/3901 days or 16.996 days

Solution And Explanation

Solution

Given,

The number of days required to finish a piece of work by Deborah = 50 days

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

And, the number of days required to finish the same work by Rebecca = 52 days

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

Here,

∵ In 50 days the work is done by Deborah = 1

∴ The work done by Deborah in 1 day = 1/50

Similarly,

∵ In 51 days the work is done by Stephanie = 1

∴ The work done by Stephanie in 1 day = 1/51

Similarly,

∵ In 52 days the work is done by Rebecca = 1

∴ The work done by Rebecca in 1 day = 1/52 part

Now, the work done by Deborah, Stephanie, and Rebecca together in 1 day

= Deborah's 1 day work + Stephanie's 1 day work + Rebecca's 1 day work

= 1/50 + 1/51 + 1/52

= 1326 + 1300 + 1275/66300

= 3901/66300 part of work

This means in 1 day, 3901/66300 part of work is done by Deborah, Stephanie and Rebecca working together.

Now, the number of days required to finish 3901/66300 part of work by Deborah, Stephanie, and Rebecca working together = 1

∴ the number of days required to finish the whole work (1 work) by Deborah + Stephanie + Rebecca together

= 1/3901/66300

= 1 × 66300/3901 = 66300/3901 days

= 16 3884/3901 days = or 16.996 days

Thus, Deborah, Stephanie, and Rebecca working together will finish the total work (1 work) in 16 3884/3901 days = or 16.996 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 Deborah = 50 days

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

And the number of days required to finish the work by Rebecca = 52 days

Thus, the number of days required to finish the work by Deborah, Stephanie, and Rebecca together = ?

Here a = 50 days

And, b = 51 days

And, c = 52 days

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

The number of days required to finish the work when Deborah, Stephanie, and Rebecca working together

= 50 × 51 × 52/50 × 51 + 50 × 52 + 51 × 52 days

= 132600/2550 + 2600 + 2652 days

= 132600/7802 days

= 132600/7802 days

= 132600 ÷ 2/7802 ÷ 2 = 66300/3901 days

= 16 3884/3901 days or 16.996

Thus, Deborah, Stephanie, and Rebecca together will finish the work in 16 3884/3901 days or 16.996 days Answer


Similar Questions

(1) If Frank can finish the work in 93 days and Randy can finish the same work in 98 days, then in how many days both can finish the work together?

(2) If David can finish the work in 13 days and Christopher can finish the same work in 18 days, then in how many days both can finish the work together?

(3) George can finish a work in 47 days. Timothy can finish the same work in 48 days while Ronald can finish the work in 49 days. How long will it take to finish it if they work together?

(4) Donna can finish a work in 42 days. Carol can finish the same work in 47 days while Amanda can finish the work in 52 days. How long will it take to finish it if they work together?

(5) If Deborah can finish the work in 54 days and Aaron can finish the same work in 59 days, then in how many days both can finish the work together?

(6) If Daniel can finish the work in 24 days and Timothy can finish the same work in 28 days, then in how many days both can finish the work together?

(7) If Patricia can finish the work in 5 days and William can finish the same work in 9 days, then in how many days both can finish the work together?

(8) If Barbara can finish the work in 13 days and Anthony can finish the same work in 17 days, then in how many days both can finish the work together?

(9) Catherine can finish a work in 100 days. Heather can finish the same work in 105 days while Diane can finish the work in 110 days. How long will it take to finish it if they work together?

(10) If Raymond can finish the work in 97 days and Eugene can finish the same work in 102 days, then in how many days both can finish the work together?


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