In: Math
The mean number of pets per household is 2.96 with standard deviation 1.4. A sample of 52 households is drawn. Find the probability that the sample mean is less than 3.11.
| a. | 
 0.2245  | 
|
| b. | 
 0.5676  | 
|
| 
 c. 0.3254  | 
||
| d. | 
 0.7726  | 
Solution :
Given that ,
mean = 
 = 2.96
standard deviation = 
 = 1.4
n = 52

= 2.96 and

= 
 / 
n = 1.4 / 
52 = 0.1941
P(
< 3.11) = P((
- 
) / 
< (3.11 - 2.96) / 0.1941)
= P(z < 0.7474)
Using standard normal table,
P(
< 3.11) = 0.7726
Probability = 0.7726
Option d)