Can someone please teach me how to do percents? i have a math test on tuesday and they just dont make any sense to me? (Increase and decrease)

In simplified exponential notation, the expression a^2•a^-3•a 1/a 0

The height of a flare fired from the deck of a ship in distress can be modeled by h(t)= -2(8t^2-52t-28), where h is the height of the flare above water and t is the time in seconds. a. find the time it takes the flare to hit the water.

Arandom sample of size n 64 is taken from a population with population proportion p 0.38 describe the sampling distribution of p. draw a graph of this probability distribution with its a. mean and standard deviation. b. what is the probability that the sample proportion is greater than 0.5? what is the probability that the sample proportion is less than 0.3? d. what is the probability that the sample proportion is between 0.35 and 0.45?