Question

Dalia owns a gravel pit. She took a random sample of rocks and counted 58 sedimentary rocks, 213 metamorphic rocks, and 522 igneous rocks.
Use the observed frequencies to create a probability model for Dalia randomly selecting one rock from her gravel pit.

Answer 1

Step One
Find the total number of rocks in the gravel pit
58 + 213 + 522 = 793

Step Two 
Set up the probabilities.
P(Sedimentary) = 58 / 793 = 0.0731
P(metamorphic) = 213/ 793 =0.2686
P(igneous) =        522 / 793 = 0.6583

Check
When these are added together the answer should be one.
0.0731 + 0.2686 + 0.6583 = 1 just as it should.