Question

Pollsters are concerned about declining levels of cooperation among persons contacted in surveys. A pollster contacts 99 people in the 18-21 age bracket and finds that 84 of them respond and 15 refuse to respond. When 276 people in the 22-29 age bracket are contacted, 257 respond and 19 refuse to respond. Assume that 1 of the 375 people is randomly selected. Find the probability of getting someone in the 18-21 age bracket or someone who agreed to respond.

Answer 1

The probability of getting someone in the 18-21 age bracket or someone who agreed to respond
`= 0.365`

Explanation:

The counts are as follows

Age Group No of people contacted No of refusals Total

18-21 88 8 96

22-29 240 42 282

Total 328 50 378

The probability of getting some one in the age bracket of 18-21 or some one who refused to respond is

`= (96)/(378) + (50)/(378) - (8)/(378) \\= (96+50-8)/(378) \\= (138)/(378) \\= 0.365`