AP Statistics Chapter 7 Random Variables

Question 1

When random variables are not independent, the variance of their sum depends on the:

Accepted Answer

Individual Variances and Correlation

Question 2

What is defined as variables which have a countable number of possible values?

Accepted Answer

Discrete Random Variables

Question 3

Suppose Mew of X = 35 and Mew of Y = 10. According to the rules for means, what is Mew X+Y?

Accepted Answer

45

Question 4

The variability of a test statistic is best described as:

Accepted Answer

amount of bias present, the stability of the population it describes, probability calculations, the spread of sampling distribution

Question 5

A continuous random variable can be found in which of the following places:

Accepted Answer

weight of a cow, height of a cow

Question 6

P(X = 0) = 0.3, P(X = 1) = 0.4, and P(X = 2) = 0.3 The mean of this probability distribution is

Accepted Answer

1

Question 7

What is the area under a probability density curve equal to?

Accepted Answer

Under the density curve and above the values of X it makes

Question 8

To reduce the variability of estimates from a simple random sample, you should:

Accepted Answer

Use a larger sample

Question 9

The correlation between two independent random variables is

Accepted Answer

zero

Question 10

P(X=0) = 0.3, P (X= 1) = 0.4, and P (X =2) = 0.3 What is the standard deviation?

Accepted Answer

0.6

Question 11

X and Y are independent. The S.D. of X is 25 and S.D. of Y is 30. What is the total S.D.?

Accepted Answer

39.051

Question 12

An error that occurs because of chance is called the:

Accepted Answer

sampling

Question 13

In the case of proportion, the sample size is large if:

Accepted Answer

np and nq are both greater than 5

Question 14

Any linear combination of independent normal variables is

Accepted Answer

Normally Distributed

Question 15

Two random variables X and y are _________ if one event doesn’t directly affect the other.

Accepted Answer

Independent

Question 16

Which of the following means the same as the expected value

Accepted Answer

mean

Question 17

Does a linear combination of independ. normal random variables have to be normally distributed?

Accepted Answer

Yes

Question 18

As the sample size increases, the S.D. of the sampling distribution of the sample mean:

Accepted Answer

decreases

Question 19

Applying CLT to the sampling distribution of the sample mean, sample is considered to be large

Accepted Answer

if n is 30 or larger

Question 20

X has a mean of 380 and standard deviation of 80. What is the P value if x >400 ?

Accepted Answer

0.2119

Question 21

What is variable whose value is a numerical outcome of a random phenomenon?

Accepted Answer

Random Variable

Question 22

The actual mean outcome of many trials gets close to the distribution mean with more trials:

Accepted Answer

Law of Large Numbers

Questions 22