1. In a normal distribution, what z -score value separates the highest 25% of th
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Question
1. In a normal distribution, what z-score value separates the highest 25% of the scores from the rest of the distribution?
a.
z = +0.67
b.
z = +1.96
c.
z = +2.81
d.
z = +0.25
____ 2. What proportion of a normal distribution is located in the tail beyond a z-score of z = 1.25?
a.
p = 0.3944
b.
p = 0.8944
c.
p = 0.1056
d.
p = 0.2266
____ 3. What proportion of a normal distribution is located between z = +0.30 and z = -0.30?
a.
p = 0.1179
b.
p = 0.3821
c.
p = 0.2358
d.
p = 0.7642
____ 4. A normal distribution has a mean of m = 50 with s = 4. What is the probability of randomly sampling an individual with a score greater than X = 52?
a.
69.15%
b.
30.85%
c.
38.30%
d.
19.15%
____ 5. What is the probability of selecting an individual with a z-score less than z = 1.65?
a.
45.05%
b.
4.95%
c.
90.10%
d.
95.05%
____ 6. What proportion of the normal distribution corresponds to the tail beyond z = –0.60?
a.
–27.43%
b.
27.43%
c.
72.57%
d.
5.48%
____ 7. What z-scores form the boundaries of the middle 70% of the distribution?
a.
z = +1.02 & z = –1.02
b.
z = +0.52 & z = –0.52
c.
z = +0.41 & z = –0.41
d.
z = +1.04 & z = –1.04
____ 8. When a random sample is selected from a population, the sample mean is not expected to be exactly equal to the population mean. On average, the size of the difference between a sample mean and the population mean is predicted by the value of the ____.
a.
standard error of M
b.
expected value of M
c.
mean of the population
d.
standard deviation of the population
____ 9. As the size of a sample increases, the size of the associated error _____.
a.
is unchanged
b.
increases
c.
decreases
d.
changes in unpredictable ways
____ 10. Which conditions would results in the least amount of error?
a.
large sample size and small amounts of variance
b.
large sample size and large amounts of variance
c.
small sample size and small amounts of variance
d.
small sample size and large amounts of variance
Constructed Responses – Remember to employ proper rounding procedures and to clearly indicate your answers for full credit. (Zero points each)
11. Compute the value of , if = 10 and n = 25.
_____
12. Compute the value of , if = 100 and n = 100.
_____
a.
z = +0.67
b.
z = +1.96
c.
z = +2.81
d.
z = +0.25
Explanation / Answer
1) Option-A)
2) Option-C)
3) Option-C)
4) Option-B)
5) Option-D)
6) Option-C)
7) Option-D)
8) Option-A)
9) Option-C)
10) Option-A)
11) error = / sqrt(n) = 10 / sqrt(25) = 10/5 = 2
12) error = / sqrt(n) = 100 / sqrt(100) = 100/10 = 10
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