Why can't standard deviation be negative?

A town is east texas received 10 inches of rain in two weeks. if it kept raining at this rate for a 31-day month, how much rain did the town recieve

Find a fraction that, when multiplied by 1/2, is less than 1/4.

How can I use number patterns to find the lcm of 120 and 360

Is 0.345 repeating rational or irrational

What two numbers multiply to get - 22 but add to get 3

What's the absolute value of $55.00

5x+12=44 then value of 5x-12=?

Which is greater, the amount the average person spends in a month on coffee or the amount the average person spends in a month on gasoline?

Using completing the square solve for x X^2-10x-9=0

Brazil exports the most coffee in the world. It cost approximately $2.55 to produce a pound of coffee; they want to make a profit of 300% for each pound. Also, the U. S. charges a 20% Tariff for each pound that is imported.