Question

The relative frequency distribution of the number of phobias reported by a hypothetical sample of 500 college students is given as follows.

0–2	0.50
3–5	0.25
6–8	0.15
9–11	0.07
12–14	0.03

(a) What is the probability that a college student expresses fewer than three phobias?


(b) What is the probability that a college student has between 3 and 11 phobias?

Answer 1

(a) To find the probability that a college student expresses fewer than three phobias.

i.e. we need to find probability that a college student less than 3 phobias that is 0,1,2 phobias

Probability of of college student in 0-2 phobias given as 0.50.

The probability that a college student express fewer than three phobias is 0.50

b) To find probability that a college student has between 3 and 11 phobias.

We need to consider probability of students in 3-5,6-8,9-11 phobias class

Hence probability between 3 and 11 phobias given by 0.25 + 0.15 + 0.07 = 0.47

PL??