Suppose that the annual rainfall in Ferndale, California, is known to be normally distributed, with a mean of 35.5 inches and a standard deviation of 2.5 inches. About 2.4% of the years, the annual rainfall will exceed how many inches? (Round your answer to one decimal place.)

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okpalawalter8 okpalawalter8 · Answer 1 · 2022-07-27T19:41:19+02:00

The average annual rainfall will be more than 40.6 inches in about 2.1 percent of the years.

Generally, the equation for the probability is mathematically given as

[tex]P( X < x) = p( Z < x - \mu / \sigma)[/tex]

Therefore

[tex]P( X > x) = 0.021[/tex]

[tex]P( X < x ) = 1 - 0.021\\\\\p( X < x) = 0.979[/tex]

[tex]P( Z < x - \mu / \sigma) = 0.979[/tex]

The z score for the probability of 0.979 is 2.034, according to the table of z values.

[tex]x - \mu / \sigma \\\\x= 2.034[/tex]

In the given equation, replace the values of mu and sigma with their respective values, and then solve for x.

[tex]x - 35.5 / 2.5 \\x= 2.034[/tex]

In conclusion, The average annual rainfall will be more than 40.6 inches in about 2.1 percent of the years.