Answer:
0.1147
Step-by-step explanation:
When adults with smartphones are randomly selected, 61% use them in meetings or classes, then
If 8 adult smartphone users are randomly selected, the probability that exactly 3 of them use their smartphones in meetings or classes can be calculated using binomial distribution as
[tex]C^8_3\cdot p^3\cdot q^{8-3}=C^8_3\cdot (0.61)^3\cdot (0.39)^5[/tex]
Note that
[tex]C^8_3=\dfrac{8!}{3!(8-3)!}=\dfrac{5!\cdot 6\cdot 7\cdot 8}{2\cdot 3\cdot 5!}=\dfrac{6\cdot 7\cdot 8}{2\cdot 3}=7\cdot 8=56,[/tex]
then the probabilty is
[tex]56\cdot (0.61)^3\cdot (0.39)^5\approx 0.1147[/tex]
