Question 1106622
z=(x-mean)/sd
(10-8)/2 or a z>1 or prob. 0.1587
(11-8)/2 or z>1.5 or prob. 0.0668
(3-8)/2=-2.5 or probability 0.0062
That is a z between 1 and 2 or 0.1359

Longer than 1000 hours is 50% or 0.5
fewer than 800 hours is a z < 2 or prob or 0.0228
between 700 and 800 is -3 < z <-2 or prob 0.0214; the next one is the same except the z values are between 2 and 3.