Question 1170481
Ho: NW=590K
HA: NW NE 590K
Level of significance is 0.01
z=2.576 critical value (+/-); reject if |z|>2.576
z=(x-mean-/sigma/sqrt(50)
=130*sqrt(50)/65=14.14, highly significant.

99% Ci: half interval is 2.576*65/sqrt(50)=23.68
the CI is (696.32, 743.68). It does not contain 590 K so again highly unlikely the true mean its 590.