Question

20 men can build a wall in 9 days, then how long would it take 12 men to build the same wall?​

Answer 1

Answer:

cline1−1\cline2−2No.of workers12No. of days\cline1−2\cline2−220x\cline1−2\cline2−29

\text{As number of workers decreaes, number of days increases}As number of workers decreaes, number of days increases

\therefore\textbf{It is inverse variation}∴It is inverse variation

\text{Since it is inverse variation, we have to apply "straight multiplication"}Since it is inverse variation, we have to apply "straight multiplication"

\implies\,20{\times}9=12{\times}x⟹20×9=12×x

\implies\,x=\dfrac{20{\times}9}{12}⟹x=1220×9

\implies\,x=\dfrac{5{\times}9}{3}⟹x=35×9

\implies\,x=5{\times}3⟹x=5×3

\implies\boxed{\bf\,x=15}⟹x=15

\therefore\textbf{15 days are required to build the same wall by 12 men}∴15 days are required to build the same wall by 12 men

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