The scores on a test are normally distributed with a mean of 140 and a standard deviation of 28. Find the score that is one-half a standard deviation below the mean. A score of
is one-half a standard deviation below the mean.

Use a graph site then you will find your answer

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First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.