Bunuel wrote:

The heights of a certain plant species are normally distributed. What height is 2 standard deviations greater than the arithmetic mean height of the plant species?

(1) The arithmetic mean height is 32.8 centimeters.

(2) The standard deviation of the heights is 2.4 centimeters.

If mean is 'x' and if standard deviation is 'y', then value which is one SD greater than mean = x + y, value which is two SD greater than mean = x + 2y, value which is three SD greater than mean = x + 3y.. and so on.

Similarly, value which is one SD lesser than mean = x - y, value which is two SD lesser than mean = x - 2y.. and so on.

Here we need x + 2y. Statement 1 gives us x, while Statement 2 gives us y. So answer

should be C.