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.

Answer 1

You 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.

Answer 2

The correct answer is option (B) 59.58 mg of vitamin C.

Explanation:

See the attached file for the calculation