Time and Work
Math MCQs

Question :    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?

Correct Answer  12 ¹²/₁₃ days or 12.923 days

Solution & Explanation

Solution

Given,

The number of days to finish the work by Daniel = 24 days

And, the number of days to finish the same work by Timothy = 28 days

Thus, the number of days to finish the work by Daniel and Timothy together = ?

Here,

∵ In 24 days the work done by Daniel = 1

∴ In 1 day, the work done by Daniel = ¹/₂₄ part

Similarly,

∵ In 28 days the work done by Timothy = 1

∴ In 1 day, the work done by Timothy = ¹/₂₈ part

Now, in 1 day, the work done by Daniel and Timothy together

= In 1 day work done by Daniel + In 1 day the work done by Timothy

= ¹/₂₄ + ¹/₂₈

= ^{7 + 6}/₁₆₈

= ¹³/₁₆₈ part of work

This means in 1 day, ¹³/₁₆₈ part of work is done by Daniel and Timothy working together.

Now, the number of days required to finish ¹³/₁₆₈ part of work by Daniel + Timothy working together = 1

∴ the number of days required to finish 1 work by Daniel + Timothy together

= ¹/_¹³/168

= 1 × ¹⁶⁸/₁₃ = ¹⁶⁸/₁₃ days

= 12 ¹²/₁₃ days = or 12.923 days

Thus, Daniel and Timothy working together will finish the work in 12 ¹²/₁₃ days = or 12.923 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 Daniel = 24 days

And the number of days required to finish the same work by Timothy = 28 days

Thus, the number of days required to finish the work Daniel and Timothy working together = ?

Here a = 24 days

And, b = 28 days

Thus, using formula ^{a × b}/_{a + b} days

The number of days required to finish the work when Daniel and Timothy working together

= ^{24 × 28}/_{24 + 28} days

= ⁶⁷²/₅₂ days

= ^{672 ÷ 4}/_{52 ÷ 4} = ¹⁶⁸/₁₃ days

= 12 ¹²/₁₃ days or 12.923

Thus, Daniel and Timothy together will finish the work in 12 ¹²/₁₃ days or 12.923 days Answer

Similar Questions

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