Question

Helen has a box of marbles. 1/2 of the marbles are yellow. 1/8 of the

marbles are red. The rest of the marbles are blue. Helen pulls one marble
out of the box at random, records its color, replaces it, and mixes up the
marbles again. If she does this 400 times, how many blue marbles should
she expect to pull out?

Answer 1

150 blue marbles

Explanation:

Hello!

If 1/2 of the marbles are yellow, and 1/8 of the marbles are red, then 3/8 of the marbles should be blue.

The percentages are as given:

• Yellow = 50%
• Red = 12.5%
• Blue = 37.5%

To calculate the possible number of blue marbles out of the 400 marbles, we can find 37.5% of 400, as there is a 37.5% chance of getting blue for each turn.

Calculate

• 37.5% of 400
• 0.375 * 400
• 150

Helen should expect to pick out 150 blue marbles.