The average yearly salary of RN’s is $70,000. If the distribution of salaries is
approximately normal with a standard deviation of $5,000,what is the probability that
a randomly selected RN makes:
Between $60,000 and $70,000 a year.
More than $70,000 a year.
Given,
=70000 , = 5000
We convert this to standard normal as
P( X < x) = P( Z < x - / )
a)
P( 60000 < X < 70000) = P( X < 70000) - p( X < 60000)
= P( Z < 70000 - 70000 / 5000) - P( Z < 60000 - 70000 / 5000)
= P( Z < 0) - P( Z < -2)
= 0.50 - 0.0228 (From Z table)
= 0.4772
b)
P( X > 70000) = P( Z > 70000 - 70000 / 5000)
= P( Z > 0)
= 0.5000 ( From Z table)
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