Question 1099328
9 total are selected.

5 use smartphones

The rest of the selection, or 4 do not

Probability that 5 use smartphones while the other four do not is:

{{{(0.61)*(0.61)*(0.61)*(0.61)*(0.61)*(0.61)*(0.39)*(0.39)*(0.39)*(0.39)}}}

The result of the multiplication is your answer.