Question 868522
t = {{{(.835 - .80)/(.3712/sqrt(400))}}} = .035/.0186 = 1.88  p(t > 1.88) = .0304
t = {{{(2.77 - 3)/(2.108/sqrt(400))}}}  = -.03/.1054 = -.2846 p(t < -.2846) = .3880
t = {{{(62600 - 65000)/(7400/sqrt(400))}}}  = -2400/370 = -6.49 p(t < -6.49) = 0
first claim: do not accept at level of significance of 0.05 
second claim: Accept
third claim:  do not accept