Answer :
The number of points that she would need to score in her 12th game in order to decrease the interquartile range by 1 point is; 23
What is the Interquartile range?
An interquartile range is one of the measure of variability that measures the spread of middle 50% of the data.
The formula to calculate interquartile range is:
IQR = Q₃ - Q₁
where;
Q₃ is third quartile
Q₁ is first quartile
The given points when arranged in increasing order gives us:
13, 15, 17, 18, 20, 20, 21, 22, 24, 25,27
Q₁ is the (n + 1)/4 terms = 3rd term.
Thus; Q₁ = 17
Q₃ is 3(n + 1)/4 term = 9th term.
Thus; Q₃ = 24
Then; IQR = 24 - 17
IQR = 7
The desired interquartile range should decrease by 1 point. Thus;
Desired IQR = 7 - 1 = 6.
To find the score of the 12th game, let us try 23 points as the score of the 12th game:
Thus;
Q₁ = 17.5
Q₃ = 23.5
IQR = 23.5 - 17.5
IQR = 6
Thus, required number of points is 23.
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