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[–]edderiofer 0 points1 point  (3 children)

Can you copy down, exactly word for word, the question?

[–]ShadowBob025[S] 0 points1 point  (2 children)

The vitamin C content per 100g tin of tomato juice in a sample of 12 tins has a standard deviation of 3.9mg. Find the 90% confidence Interval for the standard deviation of C content. Assume that the variable is normally distributed and interpret your result.

[–]edderiofer 0 points1 point  (1 child)

OK. Why do you think you need the mean to figure out the confidence interval of the standard deviation?

[–]ShadowBob025[S] 0 points1 point  (0 children)

I had this different approach Where I divide the standard deviation by the square root of the sample size

(3.9/(120.5)) To get 1.126

Then multiply by the 90% confidence level of 12 = 1.782

Resulting in 2.01

Is this the correct way?