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A can do a piece of work in 4 days and B can do the same work in 5 days. Find, how much work can be done by them working together in: one day 2 days What part of work will be left - Mathematics

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Question

A can do a piece of work in 4 days and B can do the same work in 5 days. Find, how much work can be done by them working together in:

  1. one day
  2. 2 days

What part of work will be left, after they have worked together for 2 days?

Sum
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Solution

A can do a piece of work in 4 days

and B can do the same work in 5 days

∴ A's one day's work = `1/4`

and B;s one day's work = `1/5`

(i) A and B's both one day's work = `1/4 + 1/5`

`= (5 + 4)/20 = 9/20`

(ii) A and B's 2 day's work `= 9/20 xx 2 = 9/10`

∴ work left after 2 day's = `1 - 9/10`

`= (10 - 9)/10 = 1/10`

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Chapter 7: Unitary Method (Including Time and Work) - Exercise 7 (C)

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Selina Concise Mathematics [English] Class 7 ICSE
Chapter 7 Unitary Method (Including Time and Work)
Exercise 7 (C) | Q 3

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