Probability and Statistics — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. Test scores: 70, 72, 74, 76, 100. Which measure best summarizes the typical score?
A) Median
B) Mean
C) Mode
D) Range
Median ignores extreme values, so it represents the typical score better than the mean here.
2. A baseball player got 2, 2, 3, 2, 3 hits across 5 games. Which measure best shows the most common result?
A) Mean
B) Mode
C) Median
D) Range
Mode is the value that appears most often; here 2 appears most, so mode best shows that.
3. Daily highs were 60, 62, 61, 63, 62 (deg F). Predict tomorrow's high.
A) About 50 deg
B) About 75 deg
C) About 62 deg
D) About 90 deg
The values cluster near 62, so 62 is the most reasonable next-day prediction.
4. A line plot shows lengths in feet at 1/4, 1/2, 1/2, 3/4, 1. Which length appears most often?
A) 1/4
B) 3/4
C) 1
D) 1/2
The value 1/2 appears twice, more than any other, so it is the most frequent length.
Part B: Fill in the Blank
Write the correct answer on each line.
1. In 70, 72, 74, 76, 100, the median score is 74.
The middle value of five ordered scores is 74, a typical score unaffected by 100.
2. The mean of 60, 62, 61, 63, 62 is 61.6.
Sum is 308; 308 divided by 5 equals 61.6, a fair prediction for tomorrow.
3. On a line plot with Xs at 1/4 (1), 1/2 (2), 3/4 (1), 1 (1), the total measurements is 5.
1+2+1+1 = 5 measurements, found by counting every X on the plot.
4. If a line plot shows 1/2 ft (3 Xs) and 1 ft (1 X), the total length plotted is 2.5 feet.
3 x 1/2 = 1.5 and 1 x 1 = 1, totaling 2.5 feet, a 5.MD.2 sum.
5. For test scores 80, 80, 82, 90, the mode is 80.
80 appears twice while other values appear once, so 80 is the mode.