Answer:
The sample size required is 228.
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 z-score that has a p-value of
.
The margin of error is of:

90% confidence level
So
, z is the value of Z that has a p-value of
, so
.
In previous years, the proportion has been 0.16.
This means that

Obtain a sample size that will ensure a margin of error of at most 0.04 for a 90% confidence interval.
This is n for which M = 0.04. So






Rounding up:
The sample size required is 228.