Sampling
Distributions for Means
Worksheet 2 Solutions
Back to the
worksheet.
 a) the weight of Jiffy jars, quantitative b) all
Jiffy jars; 32.3 and 0.40 are parameters,
c) 32.3; NOIt's a parameter, d) 0.2266, e)
0.2266, f) a statistic, g) 32.3 and 0.1633,
h) normal, i) 0.0329 j) 32.3, 0.0816, the
standard deviation is onehalf as large, k) 0+
 a) 0.2586 b) 0.9652 c) 0.9972
 a) The distribution is discrete (it is a count).
It may have a little right skew. 0 is the minimum
possible, 1.8 the mean, but the maximum possible
could be quite high (5 murders in a year has
some, even if a small, probability of occurring).
b) 1.8, 0.671 c) 0.0099 d) The total exceeds
2.5*25 = 62.5.
 a) the b index of a
stock on the NY Stock Exchange; it is
quantitative, b) all stocks on the NY Stock
Exchange; 1 and 0.26 are parameters, c) The
distribution is right skewed,
d) It is not possible to compute the probability:
the shape is right skewed so you can't use a
normal distribution; to find the value merely
find the relative frequency of all stocks
that have index above 1.15. e) It is a statistic;
the parameter here is 1 = mean for all stocks, f)
1 and 0.058, g) 0.0051 (1 in 196), h) I do not
choose the stocks at random: although a random
selection could lead to my average exceeding
1.15, the answer to (g) shows that this is very
unlikely. It is more reasonable to assume that my
investment strategy involves choosing
"riskier than average" stocks.
