Question

A company surveyed 1000 people on their age and the number of jeans purchased annually. The results of the poll are shown in the table. Jeans Purchased Annually 0 1 2 3 or More Total Under 12 0 69 78 73 220 12-18 10 75 70 65 220 19-25 40 77 97 76 290 over 25 36 86 128 20 270 Total 86 307 373 234 1000 A person is selected at random. Compute the probability of the following. (a) The person is over 25 and purchases 3 or more pairs of jeans annually. 0.2 Incorrect: Your answer is incorrect. (b) The person is older than 18 or purchases 1 pair of jeans annually. 0.163 Incorrect: Your answer is incorrect. (c) The person is in the age group 12-18 and purchases at most 2 pairs of jeans annually. 0.07 Incorrect: Your answer is incorrect.

Answer 1

Answer:

a) 0.02; b) 0.704; c) 0.155

Step-by-step explanation:

a) In the row of people over 25, there are 20 in the column for 3 or more; this is out of 1000 people.  This makes the probability 20/1000 = 0.02.

b) There are two rows that are greater than 18 in age, 19-25 and over 25.  This is a total of 290+270 = 560 in these two rows.  There are also 307 people that purchased only one pair of jeans; this makes a total of 560+307 = 867 people.  However, some of these are counted twice; there are 77 people in the 19-25 category that only purchased one pair and 86 people in the over 25 category that only purchased one pair.  Taking these doubles out, we have

867-(86+77) = 704 people out of 1000; this is 704/1000 = 0.704.

c) In the 12-18 category, 10 people purchased 0 pairs, 75 people purchased 1 pair and 70 people purchased 2 pairs; this is 10+75+70 = 155 people.  This is out of 1000 people; this gives us 155/1000 = 0.155.