Answer: 1692
Step-by-step explanation:
Formula to find the sample size :
Given : Confidence level :
⇒ significance level =
z-value for 90% confidence interval (using z-table)=
Prior estimate of the population proportion (p) of customers who keep up with regular vehicle maintenance is unknown.
Let we take p= 0.5
Margin of error : E= 2%=0.02
Now, the required sample size will be :
Simplify , we get
Hence, the required sample size = 1692