Very Hard Standard Deviation QS HELP! Watch

jack97
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The hourly wages, £x, of the 15 workers in a small factory are as follows:

£6.60, £3.40, £6.45, £5.20, £3.60, £7.25, £9.60, £3.75, £4.20, £8.75, £5.75, £4.50, £3.95, £4.75, £12.25

Given that SIGMAx = 90.00 and SIGMAx^2 = 631.25, calculate the mean and standard deviation of hourly wages of the workers.

Ive found out the mean which i think is £6, 90/15 = 6.
But i cant work out the SD, anyone know?

thanks
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Flauta
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(Original post by jack97)
The hourly wages, £x, of the 15 workers in a small factory are as follows:

£6.60, £3.40, £6.45, £5.20, £3.60, £7.25, £9.60, £3.75, £4.20, £8.75, £5.75, £4.50, £3.95, £4.75, £12.25

Given that SIGMAx = 90.00 and SIGMAx^2 = 631.25, calculate the mean and standard deviation of hourly wages of the workers.

Ive found out the mean which i think is £6, 90/15 = 6.
But i cant work out the SD, anyone know?

thanks
Do you know the formulas for calculating standard deviation?
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jack97
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(Original post by Flauta)
Do you know the formulas for calculating standard deviation?
yes i do, but i get the wrong answer. Ive got the answers write for the previuos 3 questions but this one isnt working
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jack97
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nevermind guys i dunno what happend must have mistyped in my calculator got the answer now
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Flauta
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(Original post by jack97)
yes i do, but i get the wrong answer. Ive got the answers write for the previuos 3 questions but this one isnt working
I'd be tempted to use \sigma=\sqrt\dfrac{\sum x^2-\dfrac{(\sum x)^2}{N}}{N} as it uses the sums you have been given.
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Flauta
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(Original post by jack97)
nevermind guys i dunno what happend must have mistyped in my calculator got the answer now
oh woops glad to hear you've got the answer now
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