mean=1.5 standard deviation=10 n=20 sample mean=1.2
1.2-1.5 = 1.3 10/4.47213 =2.236 1.3/2.236= -0.134
p value= .3669?
but i get .4483
Is it the sample standard deviation or the population standard deviation?
If the latter, than the z-statistic is appropriate and the p-value is 0.4467 (correct to four decimal places).
If the former, than the t-statistic is appropriate (provided the data come from a normal population) and the p-value is 0.4474 (correct to four decimal places).