Answer:
.
Step-by-step explanation:
We are given that,
1, 2, 3 represents someone using a coupon and 4, 5 represents someone not using a coupon.
Now, the results out of 15 trials of the experiment are given to be:
43454, 24511, 55555, 43453, 55315, 25215, 32235, 43311, 11154, 13342, 42514, 13223, 44215, 45313, 13324.
Since, we can see that, the only possibilities where 4 or more customers use coupons are:
32235, 43311, 13342, 13223 and 13324.
That is, out of 15 trials, there are total 5 trials in which 4 or more customers use coupons.
Thus, the probability of 4 or more customers using a coupon is =
.
Hence, the required probability is .