Margin of error for 68% confidence level mean is 6.5 and sd is 0.4 also margin of error for 99.7% with same mean and sd

Fredrick designed an experiment in which he spun a spinner 20 times and recorded the results of each spin

Let f(x) = 3 − x . find the average rate of change of f(x) from x = a to x = a + h and simplify your answer so that no single factor of h is left in the denominator.

Over which interval is the graph of f(x) = x2 + 5x + 6 increasing?