Probability and Statistics — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. A line plot has X's at 5(1), 6(3), 7(2), 8(4). What is the mode?
A) 8
B) 6
C) 7
D) 5
The value eight has four X marks, more than any other value.
2. A bag holds 2 red, 3 blue, and 5 green marbles. What is P(blue)?
A) 3/5
B) 3/10
C) 5/10
D) 2/10
Three blue marbles over ten total marbles equals three tenths exactly.
3. From the same bag, remove all green marbles. What is the new P(blue)?
A) 3/10
B) 2/5
C) 3/5
D) 1/2
Three blue marbles over five remaining marbles equals three fifths.
4. A bar graph shows minutes 10, 20, 30, 40. What is the median?
A) 20
B) 30
C) 35
D) 25
Middle pair twenty and thirty averages to twenty-five, the median value.
Part B: Fill in the Blank
Write the correct answer on each line.
1. A bag has 5 red, 3 blue, 2 yellow marbles. P(yellow) = 2/10.
Two yellow marbles over ten total marbles equals two tenths or one fifth.
2. Add 5 more yellow to the same bag. New P(yellow) = 7/15.
Seven yellow over fifteen total marbles equals seven fifteenths exactly.
3. A line plot has X's at 4(2), 5(3), 6(5). The mean is 5.3.
Total fifty-three divided by ten data points equals five point three.
4. A bar graph shows scores 50, 60, 70, 80, 90. The mean is 70.
Total three hundred fifty divided by five scores gives an average of seventy.
5. The same bar graph has a range of 40.
Maximum ninety minus minimum fifty equals a range of exactly forty.