- 10 Marks
Question
a. The probability that business A succeeds is 0.65 while the probability that business B
succeeds is 0.75. If the successes of the two events are independent, obtain the
probability that
i. either business A or business B or both businesses succeed (4 Marks)
ii. only one of the businesses succeeds (3 Marks)
iii. none of the two businesses succeed (3 Marks)
Answer
i. Probability that either business A or business B or both succeed:
P(A or B) = P(A) +P(B)−P (A and B)
Substituting the values:
P(A or B )= 0.65+0.75 − 0.4875 = 1.40 − 0.4875 = 0.9125
Thus, the probability that either business A or business B or both succeed is 0.9125 or 91.25%.
ii) Probability that only one of the businesses succeeds:
This is the probability that either A succeeds and B fails, or B succeeds and A fails. The formula is:
P(only one succeeds)=P(A and not B)+P(B and not A)
Where:
P(A and not
B) = P (A) × (1−P(B)) = 0.6 5× (1−0.75) = 0.65 × 0.25 = 0.1625
P (B and not A) = P (B) × (1−P(A)) = 0.75 × (1−0.65) =0.75 × 0.35 = 0.2625
Adding these together: P(only one succeeds) = 0.1625 + 0.2625 = 0.425
Thus, the probability that only one of the businesses succeeds is 0.425 or 42.5%.
iii. Probability that none of the two businesses succeed:
This is the probability that both A and B fail:
P (none succeed) = (1−P(A)) ×(1−P(B)) = (1−0.65) × (1−0.75) = 0.35×0.25 = 0.0875
Thus, the probability that none of the two businesses succeed is 0.0875 or 8.75%.
- Tags: Business Success, Independent Events, Probability
- Level: Level 1
- Topic: Statistics
- Series: MAY 2015
- Uploader: Kwame Aikins