1. If the Confidence Level is 99%, the Confidence Coefficient for calculating the confidence interval for the mean is 2.33. T or F? Why or why not? Solution False The confidence coefficient must have .005 probability in each tail. P(z > 2.575) = .005 The confidence coefficient should be 2.575.

1. 1. If the distribution of IQ is centered at 100 , and has a standard deviation of 10, then what is the
IQ Z-score of someone who has an IQ of 116?
A) 1.6
B) -1.6
C) 16
D) 0.8
E) Cannot determine
2. Bob did not study for his exam and got a z-score of -2.25. The exam had a mean of 24 and a
standard deviation of 4. What score did Bob get?
A) 15
B) 19
C) 24
D) 18
E) 11
3. In a population of people where the average weight is 160 and the standard deviation is 10,
what proportion of the people have a weight above 170?
A) 0.16
B) 0.84
C) 0.5
D) 0.34
E) Cannot determine

2. Solution
(1) Z=(X-mean)/s =(116-100)/10=1.6
Answer: A) 1.6
(2) Z=(X-mean)/s =-2.25
--> (X-24)/4 =-2.25
--> X = 24-4*2.25 = 15
Answer: A) 15
(3)P(X>170) = P(Z>(170-160)/10) =P(Z>1) =0.1586
Answer: A) 0.16