A level north west regional mock gce 2022 mathematics with statistics 3
A level north west regional mock gce 2022 mathematics with statistics 3
(i) The events A and B are such that P(A ) — and P(,A U B) — .
(ii) 25% of the population of a certain village have difficulties in hearing. A laboratory test is carried out
and the following observations were made. If someone has difficulties in hearing, the probability that the
test result is positive is 95%. If someone does not have difficulties in hearing, the probability that the test
result is negative is 90%.
A person is chosen at random from the population and tested
Find the probability that:
(a) the results are positive.
(b) the person has hearing difficulties and tests negative.
(c) the person has hearing difficulties given that he tests positive.
