question_answer 28)

The weight of 72 books is 9 kg. What is the weight of 40 such books?

Answer:

                Given, weight of 72 books = 9 kg \[\therefore \] Weight of 1 book \[=\frac{9}{72}kg\] \[\therefore \]Weight of 40 books \[=\frac{9}{72}\times 40kg=\frac{360}{72}kg=\frac{360\div 72}{72\div 72}=5kg\] [\[\because \]HCF of 360 and \[72=2\times 2\times 2\times 3\times 3=72\]] Hence, the weight of 40 books is 5 kg.