Assume that X is normally distributed with a mean μ = $64. Given that P(X ≥ $75) = 0.2981, we can calculate that the standard deviation of X is approximately:
A)$20.76.
B)$13.17.
C)$5.83.
D)$7.05.

Question

Quizplus · Accepted Answer

The correct answer is A because the standard deviation of X can be calculated using the formula σ = (x - μ) / z, where x is the value of X for which the probability is given, μ is the mean of X, and z is the z-score corresponding to the given probability. In this case, x = $75, μ = $64, and z = 0.2981, which corresponds to a probability of 0.2981. Plugging these values into the formula, we get σ = ($75 - $64) / 0.2981 = $20.76.

Assume That X Is Normally Distributed with a Mean μ