1. ## Probability

Can anybody help me with this quesiton???

To ascertain the effectiveness of the advertising campaign for the Red Cross Annual Appeal on donations, a telephone survey of 306 Brisbane residents was conducted. Two of the questions asked were
1. Did you see the advertisement for the Annual Appeal?
2. Did you donate to the Appeal?

203 of the respondents indicated they had seen the advertisement, with 13 of these not donating tothe Appeal. Overall, 80 respondents had not donated to the Appeal. If one of the respondents was chosen at random, what is the probability that he saw an advertisement and gave a donation? (3 dec pl)

Cheers

2. Originally Posted by sky_sa35
Can anybody help me with this quesiton???

To ascertain the effectiveness of the advertising campaign for the Red Cross Annual Appeal on donations, a telephone survey of 306 Brisbane residents was conducted. Two of the questions asked were
1. Did you see the advertisement for the Annual Appeal?
2. Did you donate to the Appeal?

203 of the respondents indicated they had seen the advertisement, with 13 of these not donating tothe Appeal. Overall, 80 respondents had not donated to the Appeal. If one of the respondents was chosen at random, what is the probability that he saw an advertisement and gave a donation? (3 dec pl)

Cheers
13 of those who saw the ad gave, so of the 203 who saw the ad 203-13 gave.

So p(saw ad and gave)=(203-13)/306

RonL