Statistics, Data Analysis, and Probability Flashcards

A spinner has 8 equal sections numbered 1 through 8. What is the probability of spinning an even number?

Answer: 1/2

The even numbers are 2, 4, 6, and 8 — that's 4 out of 8 sections, giving a probability of 4/8 = 1/2.

A frequency table shows that 12 students scored in the 80–89 range out of 40 total students. What percentage of students scored in this range?

Answer: 30%

12 ÷ 40 = 0.30, and 0.30 × 100 = 30%, so 30% of students scored in the 80–89 range.

Two events are independent if the outcome of one does not affect the outcome of the other. A fair coin is flipped twice. What is the probability of getting heads both times?

Answer: 1/4

Each flip has a 1/2 probability of heads; since the flips are independent, multiply: 1/2 × 1/2 = 1/4.

Which graphical display is best for showing how a single data set is distributed, including the median and quartiles?

Answer: Box plot

A box plot (box-and-whisker plot) directly displays the minimum, Q1, median, Q3, and maximum of a data set.

A data set of test scores has a mean of 78 and a standard deviation of 5. Which score is closest to 2 standard deviations above the mean?

Answer: 88

Two standard deviations above the mean: 78 + 2(5) = 78 + 10 = 88.

A survey asks 200 people whether they prefer coffee or tea. 130 prefer coffee. What is the relative frequency of people who prefer tea?

Answer: 0.35

70 people prefer tea (200 − 130 = 70), and 70 ÷ 200 = 0.35.

A line of best fit on a scatter plot has the equation y = 2x + 3. What does the slope of 2 represent in context?

Answer: For every 1-unit increase in x, y increases by 2

The slope represents the rate of change; a slope of 2 means y increases by 2 for each 1-unit increase in x.