Exercise 11 Page 318

When calculating probability, we are comparing the number of favorable outcomes to the number of possible outcomes. To calculate the probability that a randomly chosen pen is black we will use the Probability Formula. P=Favorable Outcomes/Possible Outcomes There is a total of 5 pens, so the number of possible outcomes is 5. Out of these, 2 are black, which is the number of favorable outcomes. Now we have enough information to calculate P(black pen).

P=Favorable Outcomes/Possible Outcomes

SubstituteValues

Substitute values

P(black pen)=2/5

CalcQuot

Calculate quotient

P(black pen)=0.4

WritePercent

Convert to percent

P(black pen)=40 %

The probability of choosing a black pen is 25, which can also be written as 40 %.