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Pollsters are concerned about declining levels of cooperation among persons cont

ID: 3150548 • Letter: P

Question

Pollsters are concerned about declining levels of cooperation among persons contacted in surveys. A pollster contacts 98 people in the 18-21 age bracket and finds thet 77 of them respond and 21 refuse to respond. When 281 people in the 22-29 age bracket are contacted, 238 respond and 43 refuse to respond. Suppose thet one of the 379 people is randomly selected. Find the probability of getting someone in the 18-21 age bracket or someone who responded. P(person is in the 18-21 age bracket or responded) =

Explanation / Answer

P(Person is in the 18-21 age bracket or responded)

=P(Person is in 18-21 age bracket)+P(Person responded)-P(Person is in age 18-21 bracket and responded)

=98/379+(77+238)/379-77/98

=0.25+0.83-0.78

=0.33