The distribution of vitamin C amount in vitamin drops produced by a given factory is approximately Normal, with a mean of 60.0 mg and a standard deviation of 0.5 mg. About 80% of vitamin drops contain more than A. 59.36 mg of vitamin C. B. 59.58 mg of vitamin C. C. 60.42 mg of vitamin C. D. 60.64 mg of vitamin C.

Question

The distribution of vitamin C amount in vitamin drops produced by a given factory is approximately Normal, with a mean of 60.0 mg and a standard deviation of 0.5 mg.  About 80% of vitamin drops contain more than 	 A.	59.36 mg of vitamin C. B.	59.58 mg of vitamin C. C.	60.42 mg of vitamin C. D.	60.64 mg of vitamin C.

anonymous · Answer

Yu have to calculate z-scores for each of these values and then compare them with what is needed for the 80%tile on a Normal curve.

z = (value - mean)/(standard deviation) = (value-60.0)/0.5.

z= 1 has 84% of the values smaller.