Answer:
Probability of being born in July or on a day that is a multiple of 3 = 0.42
Explanations:
Note:
Total number of months in a year = 12
Total number of days in a month = 30
Multiples of 3 = 3, 6, 9, 12, 15, 18, 21, 24, 27, 30
This means that there are 10 days that are multiples of 3 in a month
The probability of being born in July = 1 / 12
Probability of being born in a day that is a multiple of 3 = 10/30
Probability of being born in a day that is a multiple of 3 = 1/3
Probability of being born in July or on a day that is a multiple of 3 = 1/12 + 1/3
Probability of being born in July or on a day that is a multiple of 3 = 5/12
Probability of being born in July or on a day that is a multiple of 3 = 0.42