Question 1088741
95% CI is mean +/- 1.96 * s/ sqrt(n), assuming n is large enough. If not, will need to use t.
the half interval is width 2.
therefore, +/-1.96 *6.7/(sqrt(n)=2
13.132/sqrt(n)=2
square both sides
172.45=4n
n=43.11 or 44.
This requires a t, since the t-value is 2.017
will still use 44 as it was rounded up.
2.017*6.7/sqrt (44)=2.037.
try n=45
t=2.015, interval is 2.012
try n=47
t=2.013, interval is 1.97
try n=46
2.014; interval is 1.99
46.