Question 1120076
Use a z first to get an idea and then look at the t-value
the margin of error is equal to t(df=unknown)*s/sqrt)(n) and that is equal to 0.45
Start with sample size of 100
t=1.66
1.66*6.2/sqrt(100)=1.029
let n=500
1.645*6.2/sqrt(n)=0.45
10.199=0.45 sqrt(n)
22.664=sqrt (n)
n=513.67 or 514