Exercise 20 Page 930

We are told that Namid bought 20 raffle tickets out of 500 sold. Recall that the experimental probability of an event measures the likelihood that the event occurs based on the actual results of an experiment. P(Event)= Number of times the event occurs/Number of times the experiment is done We want to find the probability that Namid will not win the raffle. Note that this is a complement. The sum of the probability of an event and the probability of its complement is 1. P(Event)+P(Not event)=1 Let's start by finding the probability that one of Namid's tickets is chosen, which will be our event. The number of times the event occurs is the number of Namid's tickets, 20, and the number of times the experiment is done is the total number of tickets, 500. P( Namid)= 20/500 l← ← lNamid's tickets Total tickets The experimental probability of Namid's win is 20500. Let's now find the probability of its complement, which is Namid not winning the raffle.

P(Namid)+P(Not Namid)=1

Substitute

P(Namid)= 20/500

20/500+P(Not Namid)=1

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Solve for P(Not Namid)

SubEqn

LHS-20/500=RHS-20/500

P(Not Namid)=1-20/500

OneToFrac

Rewrite 1 as 500/500

P(Not Namid)=500/500-20/500

SubFrac

Subtract fractions

P(Not Namid)=480/500

ReduceFrac

a/b=.a /20./.b /20.

P(Not Namid)=24/25

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Convert to percent

CalcQuot

Calculate quotient

P(Not Namid)=0.96

WritePercent

Convert to percent

P(Not Namid)=96 %

The probability that Namid will not win the raffle is 2425, which can be also written as 96 %.