Question

108 identical books have a mass of 30 kg. find
(a)the mass of 150 such books
(b)the number of such books that have a mass of 20 kg

Answer 1

Answer:

(a) to get this, we just use ratio and proportion:

let x = weight of 150 books.

108 books : 30 kg = 150 books : x kg

we can thus rewrite this as

108/30 = 150/x

3.6 = 150/x

x = 150/3.6

x = 41.67 kg

(b) we also use ratio and proportion here:

let y = number of books that has weight of 20 kg.

108 books : 30 kg = y books : 20 kg

thus,

108/30 = y/20

3.6 = y/20

y = 3.6*20

y = 72 books

Step-by-step explanation:

(a) to get this, we just use ratio and proportion:

let x = weight of 150 books.

108 books : 30 kg = 150 books : x kg

we can thus rewrite this as

108/30 = 150/x

3.6 = 150/x

x = 150/3.6

x = 41.67 kg

(b) we also use ratio and proportion here:

let y = number of books that has weight of 20 kg.

108 books : 30 kg = y books : 20 kg

thus,

108/30 = y/20

3.6 = y/20

y = 3.6*20

y = 72 books