x=c(536.19, 717.47, 883.35, 640.24, 1029.02, 505.32, 756.86, 812.76)
xbar=mean(x)
xbar
sdx=200/sqrt(8)
z=abs((xbar-800)/sdx)
z
y=pnorm(z,lower.tail=FALSE)
y
p_value=2*y
p_value
#or
2*pnorm(abs(xbar-800),0,sdx,lower.tail=FALSE)