
Chapter 9
PB
Statistical Inference: Estimation for Single Populations
319
Example 9.11
The organized sector has a 70% market share in the storage batteries segment in India.
6
Suppose
a researcher wants to check this market share. For this purpose, the researcher has taken a ran-
dom sample of 120 customers of storage batteries. Out of 120 customers, 86 customers have
purchased from the organized market. Assuming customers to be normally distributed, construct
a 95% con dence interval for estimating the population proportion.
Solution: For this question, p ==
86
;
q =− =()1 0.71667 0.28333
; n = 120
The required 95% con dence interval is ...