Sally has a discount card that reduces the price of her grocery bill in a certain grocery store by 5%. If c represents the cost
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Answer: The sample size would be needed = 385
Step-by-step explanation:
Let p be the prior population proportion.
Margin of error = E
When not estimate of p is given , the formula to calculate the minimum sample size <em>n</em> = , where z* = critical value for given confidence interval.
Here z* for 95% confidence level is 1.96.
E=5%=0.05
Then
Hence, the sample size would be needed = 385