Question
Janet wanted to determine her average phone call length over 90 days. She collected the phone bills and randomly picked ten entries to look at. The phone call lengths, in minutes, are shown below.
3, 5, 16, 5, 12, 3, 12, 3, 16, 3
Assuming that the sample was representative of all the entries on the bills, what was the mean number of minutes over 90 days?
A.
7.5
B.
7.8
C.
9
D.
7.1
3, 5, 16, 5, 12, 3, 12, 3, 16, 3
Assuming that the sample was representative of all the entries on the bills, what was the mean number of minutes over 90 days?
A.
7.5
B.
7.8
C.
9
D.
7.1
Answers
GPT-4o mini
To find the mean number of minutes of Janet's phone call lengths over the 90 days, we need to calculate the average from the provided data.
The call lengths in minutes are:
3, 5, 16, 5, 12, 3, 12, 3, 16, 3
First, we calculate the sum of these call lengths:
\[
3 + 5 + 16 + 5 + 12 + 3 + 12 + 3 + 16 + 3 = 3 + 5 + 16 + 5 + 12 + 3 + 12 + 3 + 16 + 3 = 78
\]
Next, we divide by the number of entries to find the mean:
\[
\text{Mean} = \frac{\text{Sum of values}}{\text{Number of values}} = \frac{78}{10} = 7.8
\]
Therefore, the mean number of minutes is **7.8**.
The correct answer is **B. 7.8**.
The call lengths in minutes are:
3, 5, 16, 5, 12, 3, 12, 3, 16, 3
First, we calculate the sum of these call lengths:
\[
3 + 5 + 16 + 5 + 12 + 3 + 12 + 3 + 16 + 3 = 3 + 5 + 16 + 5 + 12 + 3 + 12 + 3 + 16 + 3 = 78
\]
Next, we divide by the number of entries to find the mean:
\[
\text{Mean} = \frac{\text{Sum of values}}{\text{Number of values}} = \frac{78}{10} = 7.8
\]
Therefore, the mean number of minutes is **7.8**.
The correct answer is **B. 7.8**.