Question

The data represent the murder rate per 100,000 individuals in a sample of selected cities in the United States. Find the variance and standard deviation. Round your answers to one decimal place. Class limits 5-11 12-18 19-25 26-32 33-39 40-46 Frequency 13 3 Source: FBI and U.S. Census Bureau. Download data Variance - Standard deviation-

Answer 1

Step 1: Calculation of mean:

Class interval	Mid point (x)	Frequency(f)	xf	x2 f
5 - 11	8	13	104	832
12-18	15	7	105	1575
19-25	22	7	154	3388
26-32	29	3	87	2523
33-39	36	4	144	5184
40-46	43	5	215	9245
Total =		39	809	22747

Mean () is given by:

Step 2: Calculation of variance:

Step 3: Calculation of Standard Deviaion:

s = $sqrt{156.9889}=12.5295$

Thus, the result is:

Variance = 157.0

Standard deviation = 12.6