Posted by **Julie Charmster** on Sunday, May 15, 2011 at 4:22am.

A pile of 108 identical books has a mass of 30 kg.

Find

(a)the mass of 150 books and

(b)the number of books that has a mass of 20 kg

- Math -
**Jai**, Sunday, May 15, 2011 at 4:38am
(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

hope this helps~ :)

- Math -
**Anonymous**, Tuesday, July 23, 2013 at 1:11pm
(a)

the mass of 108 books=30 kg

the mass of one book=30/108

the mass of 150 books=150*5/8

=125/8 kg

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