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RD Sharma Solutions Class 8 Mathematics Solutions for Time and Work Exercise 11.1 in Chapter 11 - Time and Work

Question 14 Time and Work Exercise 11.1

A can do a piece of work in 40 days and B in 45 days. They work together for 10days and then B goes away. In how many days will A finish the remaining work?

Answer:

The given details are,

A can do a piece of work in = 40 days

A’s 1 day work = 1/40

B can do a piece of work in = 45 days

B’s 1 day work = 1/45

(A+B)’s 1 day work together = 1/40 + 1/45

A+B’s 10 day work together = 10 (1/40 + 1/45)

= 10 ((9+8)/360) (by taking LCM for 40 and 45 which is 360)

= 10 × 17/360

= 17/36

Remaining work = 1 – 17/36

= (36 – 17)/36

= 19/36

∴ A can finish the remaining (19/36) work in = (19/36)/(1/40)

= (19/36) × 40

= 190/9

= 21 1/9 da

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