Answer:
We need at least 271 transactions
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of , we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of .
The margin of error is:
90% confidence level
So , z is the value of Z that has a pvalue of , so .
Minimum sample size within five percentage points.
n when M = 0.05.
We dont know the proportion, so we use , which would be the proportion requiring the largest sample size
Rouding up
We need at least 271 transactions