Question

calls received by a 911 operator the data show the number of calls received by a 911 operator over a period of 30 days. find the mean and modal class. \

$$\begin{tabular}{|c|c|} \\hline class & frequency \\\\ \\hline 19 - 21 & 2 \\\\ \\hline 22 - 24 & 5 \\\\ \\hline 25 - 27 & 18 \\\\ \\hline 28 - 30 & 4 \\\\ \\hline 31 - 33 & 3 \\\\ \\hline \\end{tabular}$$

\
part: 0 / 2 \
part 1 of 2 \
(a) find the mean. round your answer to one decimal place, if necessary. \
the mean number of 911 calls received is \boxed{} days.

Explanation:

Step1: Find class midpoints

For class 19-21: $\frac{19+21}{2}=20$
For class 22-24: $\frac{22+24}{2}=23$
For class 25-27: $\frac{25+27}{2}=26$
For class 28-30: $\frac{28+30}{2}=29$
For class 31-33: $\frac{31+33}{2}=32$

Step2: Calculate midpoint×frequency

$20 \times 2 = 40$
$23 \times 5 = 115$
$26 \times 18 = 468$
$29 \times 4 = 116$
$32 \times 3 = 96$

Step3: Sum products and frequencies

Sum of products: $40+115+468+116+96=835$
Sum of frequencies: $2+5+18+4+3=30$

Step4: Compute the mean

$\text{Mean} = \frac{835}{30} \approx 25.7$

Step5: Identify modal class

The class with the highest frequency (18) is 25-27.

Answer:

Mean: 25.7
Modal Class: 25-27