Question

Suppose the sediment density (g/cm) of a randomly selected specimen from a certain region is normally distributed with mean 2.65 and standard deviation 0.85.

If a random sample of 12 specimens is selected, what is the probability that the sample mean sediment density is at least 2.00 g/cm?

Answer 1

This is a normal distribution question with

Sample size (n) = 12
Since we know that


P(x > 2.0)=?
The z-score at x = 2.0 is,

z = -2.6487
This implies that
P(x > 2.0) = P(z > -2.6487) = 1 - 0.004040101160224149

PS: you have to refer z score table to find the final probabilities.
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