Big Ideas Math Algebra 1, 2015
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Big Ideas Math Algebra 1, 2015 View details
1. Measures of Center and Variation
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Exercise 20 Page 591

Practice makes perfect
a We want to find the range, and the standard deviation of the given data set.

141 116 117 135 126 121

Range

The range is the difference between the greatest and least values in a set of data. For our exercise, the greatest value is 141 and the least value is 116. Range: 141- 116=25

b To calculate the standard deviation, calculate the mean first. Let's do it!

Mean

The mean of a data set is calculated by finding the sum of all values in the set and then dividing by the number of values in the set. In this case, there are 6 values in the set.
Mean=Sum of values/Number of values
Mean=141+116+117+135+126+121/6
Mean=756/6
Mean=126

We found out that x=126.

Standard Deviation

The standard deviation of a set of data is the average amount by which each individual value deviates or differs from the mean. Standard Deviation sqrt((x_1-x )^2 + (x_2-x )^2 + ... + (x_n-x )^2/n) In the above formula, x_1, ... ,x_n are the values of the set of data, x is the mean, and n is the number of values. We have 6 values and the mean is x= 126. Let's use this value and apply the formula to each value in the set.

x_n x_n-x (x_n-x)^2
141 141-126=15 15^2=225
116 116-126=- 10 (- 10)^2=100
117 117-126=- 9 (- 9)^2= 81
135 135-126=9 9^2=81
126 126-126=0 0^2=0
121 121-126=- 5 (-5 )^2=25
Sum of Values 512

Finally, since n= 6, we need to divide by 6 and then calculate the square root. Standard Deviation: sqrt(512/6)≈ 9.24