Question 1181556
the margin of error is the half-interval for 95% or t(0.975, df=n-1)*s/sqrt(n)
use z to approximate
0.75=1.96*5.2/sqrt(n)
n=(1.96*5.2)^2/0.75^2=184.67 or 185
t is about 2% larger than z for sample size of 100
that would be 3.78 here for a larger sample size.
I would assume 3 so therefore use 3 more or a sample size of 188.
This produces an interval of (69.252, 70.748) just within 0.75. Try a sample size of 187 to see if that is better.
For n=187, the interval is (69.25, 70.25)