UNIT 1 HOMEWORK ANSWERS
Math 102 & Core 143
Note: All data below is ficticious.
1. In 1945 there were 25,000 deaths from auto accidents. In 1995, there were over 100,000
deaths from auto accidents. True or false, and explain: this shows that despite the automakers
efforts, cars have become less safe to drive.
This can probably be explained by the number of cars being driven. Unlike in 1995, most people
in 1945 did not own cars.
2. Certain studies have shown that there is an association between liver cancer and lung cancer.
Assume that drinking alcohol and smoking increase the likelihood of getting liver and lung
cancer, respectively. Do these studies show that liver cancer causes lung cancer? Do they show
that lung cancer causes liver cancer? Can you hypothesize why there might be an association
between these two cancers?
Statistical studies cannot show anything causes anything else. The link here may be that people
are most likely to smoke when they are drinking.
3. An unusual epidemic is sweeping the nation. An unusually high percentage of teenagers
think they are Britney Spears. A team of doctors at Shakira Labs are about to test a drug
to combat these delusional thoughts. A trial is set up by randomly choosing 1000 delusional
teenagers, half of which are given a placebo and the other half of which are giving the new drug.
Since the doctors want to keep this new drug secret, they perform the trial themselves, thus
knowing which teenagers are in which group. In this trial, the percentage of teenagers believing
themselves to be Britney was much higher in the placebo group. The doctors claimed success
and the drug was distributed nationwide. However, after a few months it was found that the
new drug had no measurable effect on the nation’s Britney-wannabes. What went wrong?
They did not perform a double-blind experiment. The effect here is that the doctors’ biases
affected the results of the trial.
4. Mr. X wants a new car. Since he doesn’t have the money, he’s decided to steal one. So, Mr.
X goes on the internet and finds that of 20,000 BMW 330i’s produced, 352 were stolen, and of
45,000 Nissan Sentra’s produced, 420 were stolen.
a) Which car is more likely to be stolen?
We must compare percentages. The theft rate of BMW’s is about 1.8%, while the theft rate for
Sentra’s is about .9%. Hence, the BMW is more likely to be stolen.
b) Mr. X agrees with your answer to (a) and believe that it must be easier to steal such a car.
Can you think of another reason for your answer to (a)?
It is a more desirable car to have.
