Question

Approximately 70% of U.S. adults had at least one pet as a child. We randomly survey 60 U. S. adults. We are interested in the number that had at least one pet as a child. The probability that at least 3 adults had at least one pet as a child means:

A. P(X=0)+P(X=1)+P(X=2)+P(X=3)
B. P(X=0)+P(X=1)+P(X=2)
C. P(X=4)+P(X=5)+P(X=6)+ ...
D. P(X=3)+P(X=4)+P(X=5)+ ...

Answer 1

D. P(X=3)+P(X=4)+P(X=5)+ ...

Explanation:

Given

`n =60`

`pr = 70\%` -- proportion of adults with pet

Required

Represent at least 3 adult with pet as a probability

At least 3 means 3 or more than.

So, the probability is represented as:

`P(x \ge 3) = P(3) + P(4) + P(5) + ........`

Hence;

(d) is correct