Question

1.A hypothetical population consists of eight individuals ages 14, 15, 17, 18, 19, 24, 25, and 30 years. (Enter your answers to three decimal places.)

(a) What is the probability that a person in this population is a teenager?

(b) What is the probability of selecting a participant who is at least 20 years old?

(c) What is the probability of selecting a participant older than 30?

Note that 8 is the sample space for this population.

2) Researchers often enter a lot of data into statistical software programs. The probability of making zero to two errors per 1,000 keystrokes is 0.51, and the probability of making three to five errors per 1,000 keystrokes is 0.22. Find the probabilities (per 1,000 keystrokes) associated with each of the following.

(a) at most two errors
(b) at least three errors
(c) at most five errors
(d) more than five errors

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

0–2	0.42
3–5	0.29
6–8	0.15
9–11	0.09
12–14	0.05

(a) What is the probability that a college student expresses fewer than three phobias?
(b) What is the probability that a college student expresses more than eight phobias?
(c) What is the probability that a college student has between 3 and 11 phobias?

4.) Using the unit normal table, find the proportion under the standard normal curve that lies between the following values. (Round your answers to four decimal places.)

(a) the mean and z = 1.96
(b) the mean and z = 0
(c)    z = −1.50 and z = 1.50
(d)    z = −0.50 and z = −0.20

(e)    z = 1.00 and z = 2.00

Additional Materials

Answer 1