A basketball player averaged 24 points per game over 9 games. In the first eight games his scores were 20, 22, 25, 24, 26, 23, 21, and 25. How many points did he score in the ninth game?

A basketball player averaged 24 points per game over 9 games. In the first eight games his scores were 20, 22, 25, 24, 26, 23, 21, and 25. How many points did he score in the ninth game?

• A. 28
• B. 30
• C. 32
• D. 29

Answer: (B)

When you know an average across several items, you can find the total by multiplying the average by how many items there are, and you can solve for any missing piece by balancing the total. Here, the player’s nine-game total is 9 times the average: 9 × 24 = 216 points in total. The first eight games add up to 186 points. The last game must bring the grand total to 216, so 216 − 186 = 30. The ninth game is 30 points.

When you know an average across several items, you can find the total by multiplying the average by how many items there are, and you can solve for any missing piece by balancing the total. Here, the player’s nine-game total is 9 times the average: 9 × 24 = 216 points in total. The first eight games add up to 186 points. The last game must bring the grand total to 216, so 216 − 186 = 30. The ninth game is 30 points.