Question

A bag contains 150 marbles. Some are blue, and the rest are white. There are 21 blue marbles for every 4 white marbles. How many blue marbles are in the bag? Explain your reasoning.

Answer 1

Given:

Total number of marbles in the bag = 150

There are 21 blue marbles for every 4 white marbles.

To find:

The number of blue marbles in the bag.

Solution:

Since, there are 21 blue marbles for every 4 white marbles, therefore the ratio of blue marble to white marbles is 21:4.

Let the number of blue marbles be 21x and white marbles be 4x.

Total number of marbles in the bag = 150

$21x+4x=150$

$25x=150$

Divide both sides by 25.

$x=\dfrac{150}{25}$

$x=6$

Now,

$\text{Blue marbles}=21x$

$\text{Blue marbles}=21(6)$

$\text{Blue marbles}=126$

Therefore, the number of blue marbles is 126.