# Chapter 11 - Counting Methods and Probability Theory - 11.6 Events Involving Not and Or; Odds - Exercise Set 11.6: 50

$\frac{61}{71}$

#### Work Step by Step

The probability that an event E will not occur is equal to 1 minus the probability that it will occur. P(not E)= 1 - P(E) Find the probability that a person randomly selected from the military population is not in the Marines. P(is not in the Marines) = 1 - P(is in the Marines) P(is not in the Marines) = $\frac{200000}{1420000}$ = $\frac{20}{142}$ = $\frac{10}{71}$ P(is not in the Marines) = 1 - $\frac{10}{71}$ = $\frac{71 - 10}{71}$ = $\frac{61}{71}$

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