Take this Quiz: AP Statistics — probability and sampling distributions | Zestly

Question 1

In an invented town, forty per cent of residents own a bicycle, thirty per cent own a scooter, and ten per cent own both. What is the probability that a resident chosen at random owns a bicycle, a scooter, or both?

Accepted Answer

0.6

Answer

0.5

Answer

0.8

Answer

0.7

Question 2

In an invented factory a batch of one hundred widgets contains twenty defective ones. Two widgets are drawn at random without replacement. What is the probability that both are defective?

Accepted Answer

0.038

Answer

0.04

Answer

0.19

Answer

0.39

Question 3

In an invented board game a spinner awards one point with probability 0.5, two points with probability 0.2 and three points with probability 0.3. What is the expected number of points per spin, and what does that number mean?

Accepted Answer

One point eight, the long-run average per spin, which need not be a score the spinner can actually award

Answer

Two points, the average of the three possible scores, since there are three of them and each is counted once

Answer

One point, the score most likely to come up on any single spin

Answer

One point eight, which must then be rounded to two, since the spinner cannot award a fraction of a point

Question 4

Two independent random variables $X$ and $Y$ have standard deviations $\sigma_X = 3$ and $\sigma_Y = 4$. What is the standard deviation of their sum $X + Y$?

Answer

7

Answer

25

Answer

12

Answer

5

Question 5

Which of these invented situations satisfies every requirement of the binomial setting?

Answer

Five cards are dealt from a shuffled pack and the number of red cards is counted

Answer

The heights of twenty randomly chosen pupils are measured and recorded

Answer

A fair coin is tossed ten times and the number of heads is counted

Answer

A die is rolled repeatedly until a six appears, and the number of rolls is counted