The figure shows a normal N(400, 23) distribution. Find the approximate shaded area. C.2 gives 1 - P(z

Question

The figure shows a normal N(400, 23) distribution. Find the approximate shaded area.  C.2 gives 1 - P(z < 0.74) = 1 - .7704 = .2296, or from Excel =1-NORM.DIST(417,400,23,1) = .2299.
A).3811 
B).3527 
C).2299 
D).1940

Quizplus · Accepted Answer

The shaded area corresponds to the probability of observing a value greater than 417 in a N(400, 23) distribution. Using the z-score formula, we get z = (417 - 400) / 23 = 0.74. We can then use a standard normal table or calculator to find P(z > 0.74) = 1 - P(z < 0.74) = 1 - 0.7704 = 0.2296. The closest answer choice is C, which matches this result. Therefore, the best choice is C.

The Figure Shows a Normal N(400, 23) Distribution