Stats Ch. 6

uniform

A continuous random variable has a ___________ distribution if its values are spread evenly over the range of possibilities.

find the area of the shaded region representing that probability.

Finding probabilities associated with distributions that are standard normal distributions is equivalent to__________.

a data value with an area of .85 to its left.

If you are asked to find the 85th percentile, you are being asked to find___________.

the probability that z-score is less than a.

The notation P(z<a) denotes____________.

1. Sample Proportion used to estimate a population proportion 2. Sample variance used to estimate a population variance. 3. Sample mean used to estimate a population mean.

What are statistics that are unbiased estimators of population parameters?

A z-score corresponding to an area located entirely in the left side of the curve.

What conditions would produce a negative z-score?

The right side of the horizontal scale of the graph

Where would a value separating the top 15% from the other values on the graph of a normal distribution be found?

A) The graph is uniform (Is not uniform because its graph is bell-shaped.)

Which of the following does NOT describe the standard normal distribution? A) The graph is uniform B) It is a normal distribution with a mean of 0 and a standard deviation of 1 C) The graph is symmetric D) The total area under the curve must equal 1

D) areas, probability, and relative frequencies

Which of the following groups of terms can be used interchangeably when working with normal distributions? A) z-scores, probability, and relative frequencies B) areas, z-scores, and probability C) areas, z-score, and relative frequencies D) areas, probability, and relative frequencies

C) The graph is centered around 0

Which of the following is NOT a requirement for a density curve? A) Every point on the curve must have a vertical height that is 0 or greater B) The total area under the curve must equal 1. C) The graph is centered around 0 D) The curve cannot fall below the horizontal axis.

C) A z-score is an area under the normal curve.

Which of the following is not true? A) A z-score is a conversion that standardizes any value fro a normal distribution to a standard normal distribution. B) The area in any normal distribution bounded by some score x is the same as the area bounded by the equivalent z-score in the standard normal distribution. C) A z-score is an area under the normal curve. D) If values are converted to standard z-scores, then procedures for working with all normal distributions are the same as those for the standard normal distribution.

B) A distance on the horizontal axis is given (For a standard normal curve, a z-score is a distance along the horiz. axis)

Which of the following would be information in a question asking you to find the area of a region under the standard normal curve as a solution? A) A probability is given B) A distance on the horizontal axis is given C) Finding Za D) An percentage is given

Z-Score from Areas

Work backwards by using an Area (prob) to find the distance from the mean (z-score). 1) Draw a pic 2) Use table/calc/spreadsheet

Standard Norm Distribution

μ=0 Area=1 σ=1

Uniform Distribution

A _____________ is when all values have the same prob. of occurring.

Uniform Distribution Rules

1. Area must=1 2. Height for each value is greater than or equal to 0 and less than or equal to 1.