Q: Given the contingency table for exam performance, what percent of Section B did better on Exam 2?

$$\frac{30}{49} \times 100 \approx 61.2\%$$

Question 1

Based on the scatterplot of Speed by Drop for rollercoasters, what is the direction of the relationship between Drop and Speed?

Accepted Answer

Positive

Question 2

Which of the following is NOT a condition required for correlation to be meaningful?

Accepted Answer

The variables must be measured in the same units

Question 3

If a rollercoaster with a Drop of 250 feet and a Speed of 50 mph was added to the scatterplot, what would likely happen to the correlation coefficient $$r$$?

Accepted Answer

r would decrease

Question 4

According to the correlation matrix, which two variables have the strongest negative correlation?

Accepted Answer

A and C

Question 5

Given the normal model for car speeds on Cumberland Avenue with mean $$\mu = 22.53$$ mph and standard deviation $$\sigma = 2.47$$ mph, what is the z-score for the speed limit of 25 mph?

Accepted Answer

$$z = \frac{25 - 22.53}{2.47}$$

Question 6

Using the 68-95-99.7 rule, what percent of cars would you expect to be going over the speed limit of 25 mph (mean $$=22.53$$, SD $$=2.47$$)?

Accepted Answer

About 2.5%

Question 7

If a car is captured on radar at 28 mph, would you consider the speed of the car unusual? (Mean $$=22.53$$, SD $$=2.47)$$

Accepted Answer

Yes, because its z-score is greater than 2

Question 8

For a normal distribution $$N(98.2, 0.7)$$, what percent of people have body temperatures lower than 97.14°F?

Accepted Answer

About 2.5%

Question 9

What body temperature is at the 20th percentile for $$N(98.2, 0.7)$$?

Accepted Answer

$$98.2 - (z_{0.20})(0.7)$$

Question 10

Based on the boxplot of methane emissions, which country has the highest median emission?

Accepted Answer

Italy

Question 11

Which statement is FALSE regarding the boxplot of methane emissions?

Accepted Answer

New Zealand was the most consistent on emission levels.

Question 12

What is the approximate value of the 75th percentile (Q3) for emission in Japan, based on the boxplot?

Accepted Answer

About 48,000 kilotons

Question 13

Given the contingency table for exam performance, what percent of Section B did better on Exam 2?

Accepted Answer

$$\frac{30}{49} 	imes 100 \approx 61.2\%$$

Question 14

For the data set: 23, 2, 15, 4, 9, 18, 6, 22, 5, 27, what is the median?

Accepted Answer

12.5

Question 15

Which graphical display is most appropriate for showing the distribution of a single quantitative variable?

Accepted Answer

Histogram

Question 16

Which visualization is best for comparing a quantitative variable across categories?

Accepted Answer

Side by side box plot

Question 17

True or False: Outliers can drastically impact the value of the correlation coefficient $$r.$$

Accepted Answer

True

Question 18

Which of the following is the correct formula for a z-score?

Accepted Answer

$$z = \frac{x - \mu}{\sigma}$$

Question 19

When should you use the interquartile range (IQR) instead of the standard deviation to describe spread?

Accepted Answer

When the data are skewed or have outliers

Comprehensive Statistics Exam 1 Review – Step-by-Step Guidance

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