QUESTION 11
Sets A = {x : 3 < x < 13} and B = {x : 9 < x < 25} are subsets of M = {multiples of 4 between 0 and 30}. If a number is selected at random from M, find the probability that it is in:
- A;
- B1
- A U B.
Observation
The Chief Examiner reported that the Candidates’ representation of sets A and B were very poor and hence they could not find the probability. The Candidates’ were expected to first find the universal set M = {4, 8, 12, 16, 20, 24, 28}then find sets A = {4, 8, 12}and B = { 12, 16, 20, 24}. Then, in part (a), Pr (A) = 
.
In part (b), B1 = {4, 8, 28} so that Pr (B1) = 
.
In part (c), A U B = {4, 8, 12, 16, 20, 24}, hence Pr (A U B) = 