English

If 45 persons can complete a work in 20 days, then the time taken by 75 persons will be ______ hours.

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Question

If 45 persons can complete a work in 20 days, then the time taken by 75 persons will be ______ hours.

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Solution

If 45 persons can complete a work in 20 days, then the time taken by 75 persons will be 288 hours.

Explanation:

∵ 45 persons can complete a work in 20 days.

∴ 1 person can complete a work in 45 × 20 i.e. 900 days.

Similarly, 75 persons can complete the same work in `900/75` = 12 days

= 12 × 24  ...[∵ 1 day = 24 h]

= 288 h  

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Chapter 10: Direct and Inverse Proportions - Exercise [Page 320]

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NCERT Exemplar Mathematics [English] Class 8
Chapter 10 Direct and Inverse Proportions
Exercise | Q 41. | Page 320

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