Question

In a survey at a local college, 18% of students reported that they do not own a mobile device with internet capabilities. if 20 students are selected at random, find the probability that at most 5 students don't own a mobile device with internet capabilities.

Answer 1

Answer:

0.64

Step-by-step explanation:

The probability that randomly selected student doesn't own a mobile device with internet capabilities is $p=0.18$ and the probability that randomly selected student owns a mobile device with internet capabilities is $q=1-p=1-0.18=0.82.$

If 20 students are selected at random, the probability that at most 5 students (0 students, 1 student, 2 students, 3 students, 4 students or 5 students) don't own a mobile device with internet capabilities is

$Pr=C_{20}^0p^0q^{20}+C_{20}^1p^1q^{19}+C_{20}^2p^2q^{18}+C_{20}^3p^3q^{17}+C_{20}^4p^4q^{16}+C_{20}^5p^5q^{15}=q^{20}+20pq^{19}+190p^2q^{18}+1,140p^3q^{17}+4,875p^4q^{16}+15,504p^5q^{15}\approx 0.6405021423\approx 0.64.$