A dust mite allergen level that exceeds 2 micrograms per gram (mg/g) of dust has been associated with the development of allergies. Consider a random sample of four homes and let Y be the number of homes with a dust mite level that exceeds 2 mg/g. The probability distribution for Y=y, based on a study by the National Institute of Environmental Health Sciences, is shown in the following table.

y 0 1 2 3 4

p (y).09.30.37.20.04

(a) Find the probability that three or four of the homes in the sample have a dust mite level that exceeds 2 µg/g.

(b) Find the probability that fewer than three homes in the sample have a dust mite level that exceeds 2 µg/g.

Question

Deon

Mathematics

6 October, 03:12

A dust mite allergen level that exceeds 2 micrograms per gram (mg/g) of dust has been associated with the development of allergies. Consider a random sample of four homes and let Y be the number of homes with a dust mite level that exceeds 2 mg/g. The probability distribution for Y=y, based on a study by the National Institute of Environmental Health Sciences, is shown in the following table.

y 0 1 2 3 4

p (y).09.30.37.20.04

(a) Find the probability that three or four of the homes in the sample have a dust mite level that exceeds 2 µg/g.

(b) Find the probability that fewer than three homes in the sample have a dust mite level that exceeds 2 µg/g.

+2

Answers (1)

Know the Answer?

Madeleine Russell · Answer 1

(a) 0.24

(b) 0.76

Step-by-step explanation:

We are given that let Y be the number of homes with a dust mite level that exceeds 2 mg/g. The probability distribution for Y=y is shown below;

y P (y)

0 0.09

1 0.30

2 0.37

3 0.20

4 0.04

(a) Probability that three or four of the homes in the sample have a dust mite level that exceeds 2 µg/g = P (y = 3) + P (y = 4)

= 0.20 + 0.04 = 0.24.

(b) Probability that fewer than three homes in the sample have a dust mite level that exceeds 2 µg/g = P (y = 0) + P (y = 1) + P (y = 2)

= 0.09 + 0.30 + 0.37 = 0.76.