In: Statistics and Probability
(a) The population 3, 4, 9, 14, and 20 has a mean of 10 and a standard deviation of 6.356. The z-scores for each of the five data values are
z3 ≈ −1.101,
z4 ≈ −0.944,
z9 ≈ −0.157,
z14 ≈ 0.629,
and z20 ≈ 1.573.
Find the mean and the standard deviation of these z-scores.
mean | |
standard deviation |
(b) The population 2, 6, 12, 17, 22, and 25 has a mean of 14 and a
standard deviation of 8.226. The z-scores for each of the
six data values are
z2 ≈ −1.459,
z6 ≈ −0.973,
z12 ≈ −0.243,
z17 ≈ 0.365,
z22 ≈ 0.973,
and z25 ≈ 1.337.
Find the mean and the standard deviation of these z-scores.
mean | |
standard deviation |
(c) Use the results of part (a) and part (b) to make a conjecture
about the mean and standard deviation of the z-scores for
any set of data.
The mean and standard deviation of z-scores are never the same.The mean of the z-scores is always 1, and their standard deviation is 0. The mean of the z-scores is always 1 more than the standard deviation.The mean of the z-scores is always 0, and their standard deviation is 1.
(a)
(b)
(c) The mean of the z-scores is always 0, and their standard deviation is 1.