Question

Assume that when adults with smartphones are randomly​ selected, 53% use them in meetings or classes. If 13 adult smartphone users are randomly​ selected, find the probability that fewer than 3 of them use their smartphones in meetings or classes.

The probability is ___.

​(Type an integer or decimal rounded to four decimal places as​ needed.)

Answer 1

Sample size , n =    13
Probability of an event of interest, p =   0.53

P(fewer than 3) = P(X=0) + P(X=1) + P(X=2)

P ( X =    0   ) = C(   13   ,   0   )*   0.53   ^   0   *   0.470   ^   13   =   0.0001
P ( X =    1   ) = C(   13   ,   1   )*   0.53   ^   1   *   0.470   ^   12   =   0.0008
P ( X =    2   ) = C(   13   ,   2   )*   0.53   ^   2   *   0.470   ^   11   =   0.0054

P(fewer than 3) = 0.0001 + 0.0008 + 0.0054 = 0.0063