Question

Difficulty: MediumData Distributions and Measures

The table below shows the distribution of the number of goals scored by a soccer team in each of its 1515 games last season.

Goals ScoredNumber of Games
0033
1155
2244
3322
9911

Which of the following statements best describes how the mean and the median of the number of goals scored will change if the game with 99 goals is removed from the dataset?

  1. A
    Both the mean and the median values will remain unchanged.
  2. B
    The median value will be reduced, while the mean value will not change.
  3. The mean value will be reduced, while the median value will not change.Answer
  4. D
    Both the mean and the median values will be reduced.

Answer

The mean value will be reduced, while the median value will not change.
To find the effect of removing the game with 99 goals, we compare the mean and median before and after its removal. The initial dataset has 1515 games. The median is the 8th8\text{th} value, which is 11. The initial mean is (0×3+1×5+2×4+3×2+9×1)/15=28/151.87(0 \times 3 + 1 \times 5 + 2 \times 4 + 3 \times 2 + 9 \times 1) / 15 = 28/15 \approx 1.87. If the game with 99 goals is removed, there are 1414 games remaining. The new median is the average of the 7th7\text{th} and 8th8\text{th} values, which are both 11, so the median remains 11. The new mean is (0×3+1×5+2×4+3×2)/14=19/141.36(0 \times 3 + 1 \times 5 + 2 \times 4 + 3 \times 2) / 14 = 19/14 \approx 1.36. The mean value decreases (is reduced) while the median value remains the same.

Step-by-Step Solution

1
Calculate the initial mean and median of the dataset of 1515 games.
The initial mean is approximately 1.871.87 and the initial median is 11.
To establish the baseline values before removing any data.
2
Calculate the new mean and median of the dataset of 1414 games after removing the game with 99 goals.
The new mean is approximately 1.361.36 and the new median is 11.
To determine the values after the outlier is removed.
3
Compare the initial and new values for both the mean and median.
The mean decreases from approximately 1.871.87 to 1.361.36, while the median remains 11.
To select the statement that correctly describes the change in both statistical measures.

Key Concept

Effect of outliers on mean and median
Estimated Time:1m 30s
Rate this question