![]() ![]() In such a circumstance, x is the midpoint of groups. You may be given the data in the form of groups, such as: Number Try working out the standard deviation of the above data. The formula for standard deviation becomes: When dealing with grouped data, such as the following: x Increasing each of the numbers by 2 does not make the numbers any more spread out, it just shifts them all along. This is because the standard deviation measures the spread of the data. to 3, 7, 4, 9, 5, 7 and 5), the standard deviation will be the same and the mean will have increased by the amount each of the numbers were increased by (2 in this case). 1, 5, 2, 7, 3, 5 and 3), if each number is increased by the same amount (e.g. ![]() Check your calculator's manual to see how to calculate it on yours. Click the drop-down arrow and choose 'More. Find it under the 'Insert' tab, at the far right of the toolbar, next to the 'Equation' section. Change the font to Arial Unicode MS, type an 'x' where you want the x-bar to go and then navigate to the 'Symbol' window. Do this until you have typed in all the values, then press the standard deviation button (it will probably have a lower case sigma on it). Another method of writing the x-bar symbol in Word uses the Arial Unicode MS font. Then type in the first value, press 'data', type in the second value, press 'data'. On my calculator, you go into the standard deviation mode (mode '.'). The standard deviation can usually be calculated much more easily with a calculator and this may be acceptable in some exams. n is the number of values, so in this case is 9. Now add up these results (this is the 'sigma' in the formula): 139.55ĭivide by n. ![]()
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