Statistics (Probability) , need help with this!

Question

Visit your local library: On a recent Saturday, a total of 1227 people visited a local library. Of these people, 243 were under age 10, 462 were aged 10-18, 174 were aged 19-30, and the rest were more than 30

 years old.

One person is sampled at random.(a) What is the probability that the person is less than 10

 years old?

(a) What is the probability that the person is less than 10

 years old? Round your answer to four decimal places.

(b) What is the probability that the person is more than 18

 years old?

Answer 1

Since there were 243 people under 10 and there were a total of 1227 people, the probability a person picked at random is under 10 is 243/1227 = 0.1980 The instruction to round to 4 decimal places is a little questionable. I would normally answer as a percentage which, would be 19.8044% but I think they probably just want the decimal answer 0.1980

To do question b) you must calculate the number in the final group (the over 30's) so 1227 - 243 - 462 - 174 = 348. So the number over 18 are 174 (those 19 - 30) + 348 (those over 30) = 522. So the probability of a random person being over 18 is 522/1227 = 0.4254