What is the probability that 3 customers waiting in a bank will be served in the sequence of their arrival at the bank

A.

1/6

B.

1/3

C.

1/2

D.

2/3

E.

5/6

Correct answer is A

Probability that 3 customers are attended to in the sequence they arrive 

= prob of attending to the 1st arrival x prob of attending to the second last x prob of attending to the last

= \(\frac{1}{3} \times \frac{1}{2} \times \frac{1}{1}\)

= \(\frac{1}{6}\)