Question 1184846
error=t*s/sqrt(n), but we don't know what the sample size is so can't use t initially.  Use z
0.45=1.645*4.2/sqrt(n)
square both sides and move sqrt(n) over after squaring it
0.2025 n=47.73
n=235.72 or 236

t (0.95, df=236)=1.651
at this point one would try n=237 and n=238.
0.45 is between the two for the error, so the answer is n=238.