Which of the following numbers is nearest to the probability that three randomly selected persons are born on three different days of the week ?

Options

A. `0.7`
B. `0.6`
C. `0.5`
D. `0.4`

Answer

B

Explanation

There are 7 days in a week. If 1 st person's birth day
falls on any day out of 7. So, probability is `7/7`. Since
birthday of second person will fall on any of the remaining six days then its probability `= 6/7`. And, birthday of 3rd person will fall on any of the remaining 5 days so, its probability `= 5/7`
`rArr` Probability that all three persons will have different day as their birthday
`= 7/7 xx 6/7 xx 5/7 = 30/49 = 0.612 ~~ 0.60`