UNIT 5 HOMEWORK
Math 102 & Core 143
Note: All data below is ficticious.
1. You have list of 1000 data that have been entered into Excel. You then enter a formula to
convert these into standard units. You notice that the first 10 values for the conversion are:
8.2,2.3,4.5,−.3,−.8,−6.1,5.5, .2,1.1,4.7.
You immediately check your formula and discover a mistake. How did you catch it so quickly?
2. The average on a new IQ test is 100. Assuming that these IQ scores follow a Normal
distribution, if 1% of the population has scores over 135 on this test, what is the SD for scores
on this test?
3. Suppose weekly CD sales at the Colgate Bookstore can be approximated by a normal distri-
bution with an average of $1690/wk and an SD of $160/wk.
a) What percentage of weeks have sales of more than $1850?
b) What sales level corresponds to the 29th percentile?
4. On my last exam, the average was 88 (out of 100) and the SD was 8.1. However, the data
did not follow the Normal curve; it was right-sided. True or false: there was something wrong
with the test. Explain.
