PLEASE SOLVE THIS ASAP

Question

A salon found that 20% of people who make appointments do not show up. If there are 31 appointments in total, what is the odds in favour of having fewer than 3 “no shows”? Show all your work.

Answer 1

number of people who do not show up (x) is a binomial variable with probability 0.2.

probability 0, 1 or 2 are no shows is:

C(31,0) 0.2^0 0.8^31 + C(31,1)0.2^1 0.8^30 + C(31,2) 0.2^2 0.8^29

where C(31,x) = number of combinations of 31 items taking x at a time.

= 0.00099 + 0.00768 + 0.0288 = 0.037