Question

The probability of waiting 2 minutes or longer for checkout at a particular supermarket counter is 0.3. On a given day, a man and his wife decide to shop individually at the market, each checking out at different counters. They both reach the counters at the same time. What is the probability that one or the other or both will wait 2 minutes or longer?

Answer 1

The probability answer is 69/100

Explanation:

The probability of waiting 2 minutes or longer = 0.3= (3/10)

The probability of not waiting longer = 1 - (3/10) = (7/10)

For the man,

P(waiting 2 mins or longer) = 3/10

For the woman,

P(waiting 2 mins or longer) = 3/10

Therefore,

The probability that one or the other or both will wait 2 minutes or longer

= P(man waits 2 mins or longer) or P(woman waits 2 mins or longer) or P(both waits 2 mins or longer)

= (3/10) or (3/10) or ( (3/10) and (3/10) )

= (3/10) + (3/10) + ( (3/10) X (3/10) )

= (6/10) + (9/100)

= (69/100)