Question 1

A survey of families in a county in NJ finds the mean family income is $$50,000 and the standard deviation is 20$$,000. Which statement is most accurate based only on this information?

Accepted Answer

There is not a specific number regarding the percentage of families with incomes between $$10,000 and 90$$,000

Question 2

Refer to the histograms shown in Picture 1 and Picture 2. Which statement best describes Picture 1?

Accepted Answer

The distribution is left skewed, and the median is greater than the mean

Question 3

Refer to the histograms shown in Picture 1 and Picture 2. Which statement best describes Picture 2?

Accepted Answer

The distribution is right skewed, and the median is smaller than the mean

Question 4

Which of the following statements is incorrect regarding quota sampling?

Accepted Answer

It is the probability-based equivalent of the stratified random sample

Question 5

Which of the following is an appropriate statement of inferential statistics based on a random sample of 100 students?

Accepted Answer

The mean height of all students from Rutgers is estimated to be 175cm

Question 6

Based on Figure 1 and Figure 2, which sampling strategy is best described by Figure 1?

Accepted Answer

Cluster sampling

Question 7

Based on Figure 1 and Figure 2, which sampling strategy is best described by Figure 2?

Accepted Answer

Stratified sampling

Question 8

In a classroom with 100 people, the smallest weight is 80lb and the largest is 140lb. Which of the following is a plausible value for the variance of weights?

Accepted Answer

$$100lb^2$$

Question 9

Which type of data is represented by the final letter grade for a course?

Accepted Answer

Ordinal

Question 10

Which type of data is represented by the time it takes a car to run from 0 to 60 mph?

Accepted Answer

Ratio

Question 11

Which type of data is represented by the temperature in Celsius?

Accepted Answer

Interval

Question 12

Which type of data is represented by the hair color of human beings?

Accepted Answer

Nominal

Question 13

Given a sample with mean $$\mu = 69.22$$, standard deviation $$\sigma = 1.82$$, minimum value $$68.06$$, and maximum value $$75.43$$, what is the z-score of the minimum value?

Accepted Answer

$$z = \frac{68.06 - 69.22}{1.82} = -0.64$$

Question 14

For the sequence 4, 15, 15, 8, 30, 3, 9, what is the mode?

Accepted Answer

15

Question 15

For the sequence 4, 15, 15, 8, 30, 3, 9, what is the median?

Accepted Answer

9

Question 16

For the sequence 4, 15, 15, 8, 30, 3, 9, which statement best describes the skewness?

Accepted Answer

The data is right skewed

Question 17

The percentages of blood types in a sample of 1000 people are given. Are these percentages descriptive or inferential statistics?

Accepted Answer

Descriptive statistics

Question 18

Given the following sums from a sample of 25 observations: $$\sum x = 67.5$$, $$\sum y = 100$$, $$\sum x^2$ = 188.4$$, $$\sum y^2$ = 416.2$$, $$\sum xy = 277.8$$, what is the sample correlation coefficient $$r$$?

Accepted Answer

$$r = \frac{\sum (x_i - \bar{x})(y_i - \bar{y})}{\sqrt{\sum (x_i - \bar{x})^2$ \sum (y_i - \bar{y})^2$}}$$

Question 19

In regression analysis, what is the minimum value of the function $$S(a, b) = \sum_{i=1}^n (y_i - a - b x_i)^2$ called?

Accepted Answer

Residual sum of squares

Step-by-Step Guidance for STAT211 Midterm Exam 1

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