Given that are 10 unique numbers whose mean, , is 11.8 and standard deviation is 4.729. Find the value of
- ((i))
$x_1 + x_2 + x_3 + \dots + x_{10}\
Answer -------------------------------
- ((ii))
, giving your answer to the nearest whole number.\
Answer -------------------------------
- ((iii))
Each of the value of is changed as follows:
If , then is decreased by 2.
If , then is increased by 2.Explain clearly, how this would affect the value of the standard deviation.
Answer ___
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Worked solution
15((i))
1. Use the mean formula to find the sum of the 10 numbers.
Given ,
15((ii))
1. Write the standard deviation formula and substitute the given values.
For , and standard deviation ,
2. Rearrange the formula and calculate the sum of squares.
Squaring both sides,
Hence
To the nearest whole number,
15((iii))
1. Identify how the transformation changes each value's distance from the mean.
For any value below the mean, , decreasing it by 2 makes it even further below .
For any value above the mean, , increasing it by 2 makes it even further above .
2. Conclude the effect on the standard deviation.
Since the data values become more spread out from the mean, the standard deviation becomes larger.
The standard deviation would increase, because each value is moved further away from the mean, increasing the spread of the data.
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