Ihave trouble with these questions

18.

Use the formula for the circumference of a circle.

Now enter the information you are given. You are told the circumference is 28pi, so replace C with 28pi and solve for r, the radius.

Switch the sides.

Divide both sides by 2pi.

B 14 m

19.

Look at a point on the graph. For example, when x = 4, y = 2 which is point (4, 2). x represents the number of songs. y represents the cost. The point (4, 2) means that 4 songs cost $2. Divide $2 per 4 to find a unit rate of cost of songs. $2/4 = $0.5 per song. Each song costs $0.50. If you multiply the number of songs by 0.5, you get the cost in dollars. The number of songs is x. The price of x songs is 0.50x. The price is y, so the equation is y = 0.50x.

B y = 0.50x

24

step-by-step explanation:

the above table 1 will calculate the population size (n) after a certain length of time (t). all you need to do is plug in the initial population number (no), the growth rate (r) and the length of time (t). the constant (e) is already entered into the equation. it stands for the base of the natural logarithms (approximately 2.71828). growth rate (r) and time (t) must be expressed in the same unit of time, such as years, days, hours or minutes. for humans, population growth rate is based on one year. if a population of people grew from 1000 to 1040 in one year, then the percent increase or annual growth rate is 40/1000 x 100 = 4 percent.

step-by-step explanation: