The mean plus or minus one standard deviation defines the percent probability range of a normal distribution. 82 68 95 50 90

For what is the measure of the angle at the top of the shed? a. multiplication of areas b. squaring of areas c. addition of areas d. division of areas

Adriveway is 40 yards long about how many meters long is it

[10 points, algebra 2-simplifying complex fractions]according to my answer key the restrictions are -1 and 4. but why not positive 1?