10. Incorrect. The answer is
true, not false
First, find standard units (z). Z = [(100)2/125) + (200)2/125](1/2)
= 20 hours
The difference 160 hours in standard units (z) = (160-200)/20 = -2
The required probability = (area under normal curve to right of z = -2)
= (.5000 + .4772 ) =
.9772
The difference 250 hours in standard units (z) = (250-200)/20 = 2.50
The required probability = (area under normal curve to right of z = 2.50)
= (.5000 - .4938) = .0062