Review For PreLim 1

Question 1

For a continuous random variable X, P(y<X<=x) = P(X <= x) - P(X <= y) for all values of x > y. Why is that the case?

Answer 1

Probability is the area under the curve, which in this case is the probability density function. If you take the difference of the area, you are left with a small section of it.

Question 2

If you have a continuous distribution, do you need to follow the R limitation that it can only do less or equal and greater?

Answer 2

No

Question 3

If you don’t have x and need to find x in a distribution while given P, you use what R code?

Answer 3

qdistribution(p, df, lower.tail)

Question 4

dnorm is equal to?

Answer 4

The height at that point in the pdf.

Question 5

When do you do p(x)^y?

Answer 5

When you are finding the probability of many randomly selected things.

Question 6

Does the mean have to be in the sample space?

Answer 6

No, it does not.

Question 7

The 50th percent/second quartile is always the?

Answer 7

Median.

Question 8

Each quartile is?

Answer 8

50% from the previous quartile.