Question

Song randomly pulled a marble from a bag, recorded its color, put it back, and repeated. The results are shown in the following table.

Color Frequency

Blue 22

Green 19

Purple 20

Red 18

Yellow 21


If Song were to repeat the experiment 25 more times, how many of those times should he expect to pull a purple marble?


Enter your answer as a number, like this: 42

Answer 1

Explanation:

when counting the events we see, he did

22+19+20+18+21 = 100 experiments.

and he got in 20 cases out of the possible 100 a purple marble.

that means the observed probability to pull a purple marble is 20/100 = 1/5.

now he does 25 more pulls.

each with the probity of 1/5 to pull a purple marble.

so, he should expect to pull a purple marble 25×1/5 = 5 times.