AP Stats CH3 Review

If heights of 3rd graders follow a normal disturction with a mean of 52 inches and a standard deviation of 2.5 inches, what is the z score for a 3rd grader who is 47 inches tall?

• -5

• -2

• 2

• 5

Suppose that a normal model describes the acidity (pH) of rainwater, and that water tested after last week's storm has a z-score of 1.8.  This means that the acidity of the rain

• had a pH 1.8 higher than average rainfall

• had a pH of 1.8

• varied with a standard devation of 1.8

• had a pH 1.8 standard deviation higher than that of average rainwater

In a factory the weight of the concrete poured into a mold by a machine follow a normal distrubtion with a mean of 1150 pounds and a standard deviation of 22 pounds.  Approximately 95% of molds filled by this machine will hold weights in what interval?

• 1084 - 1216

• 1106 - 1150

• 1106 - 1194

• 1128 - 1172

Which of the following are true?
I) In a normal distribution the mean is always equal to the median
II)All unimodal and symmetric distrubtions are normal for some value of mean and standard deviation
III) In a normal distribution, nearly all of the data is within 3 standard deviations of the mean

• I only

• II only

• III only 

• I and III only

• A

• B

• C

• D

• E

Is this a probability distribution?

• No, the sum of p(x) does not equal 1.

• Yes, all p(x) are between 0 and 1.

• No, all p(x) are not between 0 and 1.

• Yes, the sum p(x) is 1.

Is this a probability distribution?

• No

• Yes

The heights of mature pecan trees are approximately normally distributed with a mean of 42 feet and a standard deviation of 7.5 feet. What proportion of pecan trees are between 43 and 46 feet?

• .1501

• .2969

• .4470

• .5530

Data was collected on two variables x and y and a least squares regression line was fitted to the data.  The resulting equation is y = -2.29 + 1.70x.  What is the residual for the point (5, 6)

• -2.91

• -0.21

• 0.21

• 6.21

The correlation between the fathers' heights and the heights of their 16 year old sons is most likely to be...

• near -1.0

• near 0

• near 0.7

• exactly 1