Probability and Statistics — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. House prices: 200k, 210k, 215k, 220k, 900k. Which measure best summarizes a typical price?
A) Median
B) Mean
C) Mode
D) Range
Median is not pulled by 900k, so it best represents the typical price here.
2. Shoe sizes sold today: 7, 8, 8, 9, 10. Which measure best helps the store restock?
A) Range
B) Mode
C) Median
D) Mean
Mode shows the most frequent size (8), which the store should restock most.
3. Weekly rainfall (in): 0.5, 0.6, 0.5, 0.7, 0.6. Predict next week's rainfall.
A) About 0.1 in
B) About 1.5 in
C) About 0.6 in
D) About 3.0 in
Values cluster near 0.6 in, so 0.6 in is the most reasonable next-week prediction.
4. A line plot has Xs at 1/4 (2), 1/2 (3), 3/4 (1). Which length appears MOST?
A) 1/4
B) 3/4
C) 1
D) 1/2
1/2 has 3 Xs, more than any other value, so it appears most often on the plot.
Part B: Fill in the Blank
Write the correct answer on each line.
1. Median of 200, 210, 215, 220, 900 (in thousands) is 215 thousand.
The middle value of five ordered prices is 215 thousand, resistant to the 900 outlier.
2. The mean of 0.5, 0.6, 0.5, 0.7, 0.6 inches is 0.58.
Sum is 2.9; 2.9 divided by 5 equals 0.58 inches as the average rainfall.
3. On a line plot with Xs at 1/4 (2), 1/2 (3), 3/4 (1), total Xs = 6.
2 + 3 + 1 = 6 total measurements counted across the line plot.
4. Line plot total length: 1/4 ft x 2 + 1/2 ft x 2 + 3/4 ft x 2 = 3 feet.
2/4 + 2/2 + 6/4 = 1/2 + 1 + 3/2 = 3 feet using 5.MD.2 reasoning.
5. Mode of shoe sizes 7, 8, 8, 9, 10 is 8.
Size 8 appears twice while the others appear once, making 8 the mode.