Question

Students of Keystone/K12! Many points

Candace has a bag with 20 marbles in it. Some of the marbles are blue, some are green, and some are yellow. She draws one marble at random, records the color, and returns it to the bag. Here is her data after 1000 trials:

Blue Green Yellow


307 642 51

Estimate the probability that a marble drawn at random will be blue.
Estimate the probability that a marble drawn at random will be green.
Estimate the probability that a marble drawn at random will be yellow.
Express each probability estimate as a fraction with 20 in the denominator.

Answer 1

It is very easy. To find the experimental probability of each, you have to divide the number for each color by 1000. Then, multiply it by 20 to find the amount expected out of 20.

Blue: 307 / 1000 = 0.0307 0.0307 × 20 = 6.14

Green: 642 / 1000 = 0.642 0.642 × 20 = 12.84

Yellow: 51 / 1000 = 0.051 0.051 × 20 = 1.02

Answer 2

Blue

P(blue) = 307 / 1000 = 0.307

Green

P(Green) = 642/1000 = 0.642

Yellow

P(Yellow) = 51/1000 = 0.051

To make the denominator 20, you are going to have to divide both numerator and denominator by 50. 1000/50 = 20

Blue= 307/50 = 6.14; P(blue) 6.14/20

Green = 642/50 = 12.84; P(blue) = 12.84 / 20

Yellow = 51/50 = 1.02; P(yellow) = 1.02/20

Check

Add these three together

1.02 + 12.84 + 6.14 = 20 as it should.