Statistics 1060

Solutions to Practice Problems for Week 2

1.

a)
The mean monthly salary would increase by \$70.
The standard deviation would be unchanged.
b)
The average monthly salary would increase by 5% and the standard deviation would increase by 5% as well.

2.

a)
mean = 2.5
b)
0.23, 0.30, 0.02
c)
median = 2, Q1 = 1, Q3 = 3, IQR = 2, LIF = 1-1.5(2) = -2, UIF = 3 + 1.5(2) = 6, Lower adjacent score = 0, Upper adjacent score = 6, there are no outliers.

The middle 50% of the distribution is symmetrical but there is skewness in the tails. The right hand tail is longer than the left showing skewness to the right.

d)
The mean is 2.51 which is larger than the median of 2. We would expect the mean to be larger than the median since the distribution is skewed to the right.
e)
s = 1.44
The interval + 2s is (-.37, 5.39).
97 out of 100 observations (or 97% ) fall in this interval.

Answers to 1.69, 1.71, 1.77, 1.79, 1.81, 1.87, 1.91, 1.95 in back of the text

More complete solutions to many of the practice problems from the text can be found in Study Guide for Moore and McCabe's Introduction to the Practice of Statistics

(available in Math/Stats Learning Centre)