Exhibit 6-9
The average price of personal computers manufactured by MNM Company is $1,200 with a standard deviation of $220. Furthermore, it is known that the computer prices manufactured by MNM are normally distributed.
-Refer to Exhibit 6-9. If 513 of the MNM computers were priced at or below $647.80, how many computers were produced by MNM?
A)185,500
B)85,500
C)513,000
D)not enough information is provided to answer this question

Question

Quizplus · Accepted Answer

Using the z-score formula, z = (X - mean)/SD, we can find the z-score for $647.80: z = ($647.80 - $1,200)/$220 = -2.46. Looking up the probability associated with a z-score of -2.46 in a standard normal distribution table, we find that the probability of a computer being priced at or below $647.80 is 0.007. Multiplying this probability by the total number of computers produced by MNM gives us: 0.007x = 513, where x is the total number of computers. Solving for x gives us x = 85,500. Therefore, the answer is B.

Exhibit 6-9 The Average Price of Personal Computers Manufactured by MNM Company