Question

Sheila either walks or cycles to school The probability that she walks to school is 0.65 If she walks, the probability that she is late is 0.4 If she cycles, the probability that she is late is 0.1 What is the probably that on any one day Sheila is not late for school.

Answer 1

Probability that she walks or cycle to school on any day and not be late is 0.705

Explanation:

Part A

P(she walks to school) = 0.65

P(she will be late) = 0.4

P(she will not be late) = 1 - P(she will be late) = 1 - 0.4 = 0.6

Part B

P(she cycle to school) = 1 - P(she walks to school) = 1 - 0.65 = 0.35

P(she will be late) = 0.1

P(she will not be late) = 1 - P(she will be late) = 1 - 0.1 = 0.9

Thus, probability that she walks or cycle to school and not be late =

P(walks: not late) + P(cycle: not late)

= (0.65 x 0.6) + (0.35 x 0.9)

= 0.39 + 0.315

= 0.705

Therefore, probability that she walks or cycle to school on any day and not be late is 0.705