Employees that work at a fish store must measure the level of nitrites in the water each day. Nitrite levels should remain lower than 5 ppm as to not harm the fish. The nitrite level varies according to a distribution that is approximately normal with a mean of 3 ppm. The probability that the nitrite level is less than 2 ppm is 0.0918. Which of the following is closest to the probability that on a randomly selected day the nitrite level will be at least 5 ppm(A) 0.0039
(8) 0.0266
(C) 0.0918
(D) 0.7519
(5) 0.9961

(A) 0.0039

Step-by-step explanation:

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean and standard deviation , the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

The probability that the nitrite level is less than 2 ppm is 0.0918.

This means that when , Z has a pvalue of 0.0918. So when X = 2, Z = -1.33.

We use this to find

Which of the following is closest to the probability that on a randomly selected day the nitrite level will be at least 5 ppm

This is 1 subtracted by the pvalue of Z when X = 5. So

has a pvalue of 0.9961

1 - 0.9961 = 0.0039

So the correct answer is:

(A) 0.0039

a framing bias

step-by-step explanation:

rodrigo is subject to a framing bias i believe.