An arrow is shot vertically upward at a rate of 210 feet per second. Use the projectile formula h = −16t2 + v0t to determine at what time t (in seconds) the height of the arrow will be 400 feet.

Abox contains 1 plain pencil and 4 pens. a second box contains 5 color pencils and 5 crayons. one item from each box is chosen at random. what is the probability that a plain pencil from the first box and a color pencil from the second box are selected? write your answer as a fraction in simplest form.

Jose predicted that he would sell 48 umbrellas. he actually sold 72 umbrellas. what are the values of a and b in the table below? round to the nearest tenth if necessary

What is the domain of the step function f(x)=[2x]-1?