Question

A computer algorithm is going to pick a day at random from the seven days of

the week.
The table below shows the probabilities of the algorithm choosing each of the
weekdays.
Weekdays
Probability
Monday
0.12
Tuesday Wednesday Thursday
0.07
0.05
0.28
Work out the probability that it will not choose one of the weekdays.
Friday
0.15

Answer 1

The sum of the probabilities of choosing each weekday is:

0.12 + 0.07 + 0.05 + 0.28 + 0.15 + p(Friday) + p(Weekend) = 1

where p(Friday) is the probability of choosing Friday and p(Weekend) is the probability of choosing one of the weekend days (Saturday or Sunday).

We know that the probability of choosing one of the weekdays is:

p(Weekdays) = 0.12 + 0.07 + 0.05 + 0.28 = 0.52

So, the probability of not choosing one of the weekdays is:

p(Not Weekdays) = 1 - p(Weekdays) = 1 - 0.52 = 0.48

Therefore, the probability that it will not choose one of the weekdays is 0.48.