The number of homes sold each year by a
realtor is normally distributed with a mean of
54. If the realtor sold 36 homes last year
with a z-score of -2.4, what is the standard
deviation?

Do the inverse operation

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.

X=14 hope it !