a From the table find the number of data points that sent more than 70 messages each day.
B
b From the table find the number of data points that sent less than 50 messages each day.
A
a About 0.267
B
b About 0.267
Practice makes perfect
a We will estimate the population proportion of teen phone users who send more than 70 messages per day. Therefore, from the table we will count the number of teens who send more than 70 messages each day.
Number of Text Messages
30
60
59
83
41
37
66
63
60
92
53
42
47
32
79
53
80
41
51
85
73
71
69
31
69
57
60
70
91
67
From the table we can see that the number of data points that have a greater value than 70 is 8. That is, 8 teens out of 30 sent more than 70 messages each day. By using this information we can find . =8/30≈ 0.267
b This time we will estimate the population proportion of teen phone users who send fewer than 50 messages per day. To do so we will count from the table the number of teens who send fewer than 50 messages each day.
Number of Text Messages
30
60
59
83
41
37
66
63
60
92
53
42
47
32
79
53
80
41
51
85
73
71
69
31
69
57
60
70
91
67
By looking at the table we can say that 8 out of 30 teens sent less than 50 messages each day. Using this information, let's find . =8/30≈ 0.267
