Q: What is the formula for the midpoint of a class interval using the Pearson method?

$$x_i = \frac{\text{Lower Limit of Class } i + \text{Lower Limit of Class } (i+1)}{2}$$

Question 1

Which symbol represents the population mean in statistics?

Accepted Answer

$$\mu$$

Question 2

Given the histogram of SAT Math scores, what is the total number of students sampled?

Accepted Answer

250

Question 3

What is the formula for the sample variance?

Accepted Answer

$$s^2$$ = \frac{\sum (x_i - \bar{x}$$)^2$$}{n-1}$$

Question 4

A bar chart shows that 42.5% of respondents prefer Solar Power. If 1,200 people were surveyed, how many chose Solar Power?

Accepted Answer

510

Question 5

Which of the following best describes the shape of the SAT Math score distribution in the histogram?

Accepted Answer

Bell-shaped (symmetric)

Question 6

What is the formula for the midpoint of a class interval using the Pearson method?

Accepted Answer

$$x_i = \frac{	ext{Lower Limit of Class } i + 	ext{Lower Limit of Class } (i+1)}{2}$$

Question 7

If the sample mean of 10 test scores is 79.7 and the sum of squared deviations is 952.10, what is the sample standard deviation?

Accepted Answer

$$s = \sqrt{\frac{952.10}{9}} = 10.3$$

Question 8

Which of the following is a parameter, not a statistic?

Accepted Answer

$$\sigma$$

Question 9

Given the stem-and-leaf plot with stems 1, 2, 3, 4 and leaves as shown, what is the median of the dataset: 12, 15, 20, 23, 27, 31, 34, 34, 38, 42, 46?

Accepted Answer

31

Question 10

A grouped frequency table has midpoints 15, 25, 35 with frequencies 4, 6, 2. What is the grouped sample mean?

Accepted Answer

$$\bar{x} = \frac{280}{12} = 23.3$$

Question 11

If a dataset has values 55.4, 70.5, 76.2, 80.1, 82.7, 88.3, 112.8, 118.0, what is the median?

Accepted Answer

$$(80.1 + 82.7)/2 = 81.4$$

Question 12

Which formula would you use to calculate the population variance?

Accepted Answer

$$\$$sigma^2$$ = \frac{\sum (x_i - \mu)^2$}{N}$$

Question 13

In the histogram, what percentage of students scored at least 120 on the SAT Math test?

Accepted Answer

20.0%

Question 14

Which of the following is NOT a measure of central tendency?

Accepted Answer

Standard deviation

Question 15

If $$x_1 = 5$, x_2$ = 9$$, $$x_3 = 13$, x_4$ = 17$$, what is $$(x_1$ + x_3$ + x_4$)/3$$?

Accepted Answer

$$(5 + 13 + 17)/3 = 11.7$$

Question 16

Which of the following best describes a statistic?

Accepted Answer

A numerical summary calculated from a sample

Describing and Summarizing Data: Central Tendency, Dispersion, and Graphical Methods

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