Question 973816
The probability that none do is (0.84^8)=0.2479
The probability that at least one will is 1- probability (0)=0.7521.

At least 5 use it
5: 8 choose 5: 56 ways *(0.16^5)(0.84^3)=0.0035
6: 8 choose 6: 28 ways *(0.16^6)(0.84^2)=0.0003
7: 8 ways (0.17^7)(0.84)=0.00003
8 will be too small.
Probability is 0.0038

The expected value is about 1, where the probability is 0.38
for 2 it is 28 *(0.84^6)(0.16^2)=0.25
For 0,1,2 using it, the probability is nearly 90%.


It is 8 choose the number using (n), multiplied by (0.84^n)(0.16^8-n)