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The next presidential election. A recent study suggested that 70% of all eligible voters will vote in the next presidential election. Suppose 20 eligible voters are randomly selected from the population of all eligible voters.

a. Analyze the potential outcomes for the sample using the binomial random variable.

b. Use a binomial probability table to find the probability that more than 12 of the eligible voters sampled will vote in the next presidential election.

c. Use a binomial probability table to find the probability that more than 10 but fewer than 16 of the 20 eligible voters sampled will vote in the next presidential election.

Short Answer

Expert verified
  1. A binomial random variable can have any number between 0 as well as n.
  2. PX⩾12=0.772
  3. P16⩽X⩽20=0.714

Step by step solution

01

Given information

70% of all eligible voters will vote in the next presidential election

n=20

02

(a)Finding potential outcomes

The experiment comprises of n similar as well as independent trials, with n predetermined. Every trial can have one of two results: success (S) as well as failures (F), with the likelihood of succeeding (p) being equal from trial to trial. A binomial random variable can have any number between 0 as well as n.

03

(b) Finding the probability that more than 12 of the eligible voters sampled will vote in the next presidential election

PX⩾12=PX=12+PX=13+...+PX=20=∑i=122020ipi1-p20-i=0.772

Thus, the required probability is 0.772.

04

(c) Finding the probability that more than 10 but fewer than 16 of the 20 eligible voters sampled will vote in the next presidential election

P16⩽X⩽20=PX=16+PX=17+...+PX=20=∑i=162020ipi1-p20-i=0.714

Thus, the required probability is 0.714.

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