College

In this problem, we explore the effect on the standard deviation of multiplying each data value in a data set by the same constant. Consider the data set 17, 11, 15, 14, 16.

(a) Use the defining formula, the computation formula, or a calculator to compute [tex]s[/tex]. (Round your answer to one decimal place.)

[tex]s = [/tex]

(b) Multiply each data value by 4 to obtain the new data set 68, 44, 60, 56, 64. Compute [tex]s[/tex]. (Round your answer to one decimal place.)

[tex]s = [/tex]

(c) Compare the results of parts (a) and (b). In general, how does the standard deviation change if each data value is multiplied by a constant [tex]c[/tex]?

- Multiplying each data value by the same constant [tex]c[/tex] results in the standard deviation being [tex]|c|[/tex] times as large.
- Multiplying each data value by the same constant [tex]c[/tex] results in the standard deviation increasing by [tex]c[/tex] units.
- Multiplying each data value by the same constant [tex]c[/tex] results in the standard deviation being [tex]|c|[/tex] times smaller.
- Multiplying each data value by the same constant [tex]c[/tex] results in the standard deviation remaining the same.

(d) You recorded the weekly distances you bicycled in miles and computed the standard deviation to be [tex]s = 2.1[/tex] miles. Your friend wants to know the standard deviation in kilometers. Do you need to redo all the calculations?

- Yes
- No

Given 1 mile ≈ 1.6 kilometers, what is the standard deviation in kilometers? (Enter your answer to two decimal places.)

[tex]s = [/tex] km

Answer :

Final answer:

The standard deviation increases proportionally when each data point in a set is multiplied by a constant. This is demonstrated by a data set (17, 11, 15, 14, 16) that when multiplied by a constant (4), results in the standard deviation being four times larger. Additionally, it's unnecessary to redo all calculations when the measurements change, for example from miles to kilometers, the standard deviation can just be multiplied by the conversion factor.

Explanation:

When you are asked to compute the standard deviation 's' for the data points 17, 11, 15, 14, 16, you will do so by following the formula for calculating standard deviation, which includes summing the squares of the differences between each data point and the mean, before dividing by the number of data points, and taking the square root. This will result in a value of 's' which we rounded to 1 decimal place, as per your instructions.

For part 'b', when each data point is multiplied by the constant 4, the resulting data set 68, 44, 60, 56, 64 will give a computed standard deviation 's' of 4. The new 's' is four times as large as the initial 's', corresponding with the constant we multiplied by.

The standard deviation increases by a factor equal to the absolute value of the constant when each data point in a data set is multiplied by a constant 'c'. This leads us to believe that the standard deviation does not remain the same, nor does it become smaller, but is |c| times larger when multiplying each data observation by c.

Finally, you do not need to redo all the calculations if you change to measurements in kilometers. Since 1 mile is approximately 1.6 kilometers, simply multiply your current standard deviation by 1.6 to obtain your new 's' in kilometers. Thus, the standard deviation in kilometers would be approximately 3.36 (rounded to two decimal places, as indicated).

Learn more about standard deviation here:

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Answer:

Step-by-step explanation:

a) Mean = (17 + 11 + 15 + 14 + 16)/5 = 14.6

Standard deviation = √(summation(x - mean)²/n

n = 5

Summation(x - mean)² = (17 - 14.6)^2 + (11 - 14.6)^2 + (15 - 14.6)^2 + (14 - 14.6)^2 + (16 - 14.6)^2 = 21.2

Standard deviation = √(21.2/5 = 2.06

Approximating to 1 decimal place, s = 2

The new data set is

68, 44, 60, 56, 64

Mean = (68 + 44 + 60 + 56 + 64)/5 = 58.4

Summation(x - mean)² = (68 - 58.4)^2 + (44 - 58.4)^2 + (60 - 58.4)^2 + (56 - 58.4)^2 + (64 - 58.4)^2 = 339.2

Standard deviation = √(339.2/5 = 8.24

c) The standard deviation of the new data is 4 times the standard deviation of the previous data

In general, multiplying each data value by the same constant c results in the standard deviation being |c| times as large.

d) s = 2.1 miles

Since 1 mile = 1.6 kilometers, the constant with which we would multiply the given standard deviation is 1.6. Therefore, converting to kilometers, it becomes

1.6 × 2.1 = 3.36 km