Answer:
170
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 of:

Assume:

90% confidence level
So
, z is the value of Z that has a pvalue of
, so
.
What is the smallest sample size required to obtain the desired margin of error?
This is n for which M = 0.03. So






Rounding up, 170.