a. Since Rachel tutors English for 50 dollars for each hours, her rate is 50 dollar per hour. If she tutors for time, H hours, Her earning E = rate × time = 50 × H

E = 50H.

b. If Rachel's earnings after tutoring for 19 hours is gotten by substituting H = 19 into the equation for the earnings, E.

So, E = 50H

E = 50 × 19

E = 950 dollars.

So, Rachel's earnings after 19 hours is 950 dollars.

4 0

3 years ago

A population of bacteria is initially 2,000. After three hours the population is 1,000.

lina2011 [118]

The population starts at 2000, so a=2000.

We also know that the population in 3 hours is 1000, so we can setup the equation:

2000 b^3 = 1000

This gets us:

b^3 = 1/2

And taking the cube root of both sides gives us:

b ≈ 0.7937005259841

Rounding that to 4 places, we have:

f(t) = 2000 (0.7937)^t

5 0

3 years ago