<span>25.7 years
The rule of 72 is a simple approximation on how long it will take to double your money. You simply divide 72 by the interest rate and you'll have your estimate on the number of years it will take. So
72 / 2.8 = 25.7 years.
To demonstrate that it's just an estimate, you can take the log of 2 and divide by the log of 1.028 to get the exact value. This far more complicated calculation gives the result of 25.1 years. And to be honest, the estimate of 25.7 years is more than close enough for such an quick and easy rule of thumb.</span>
Y=8
your teacher is introducing algebra
You are given two points in the linear function. At time 0 years, the value is $3000. At time 4 years, the value is $250. This means you have points (0, 3000) and (4, 250). You need to find the equation of the line that passes through those two points.
y = mx + b
m = (y2 - y1)/(x2 - x1) = (3000 - 250)/(0 - 4) = 2750/(-4) = -687.5
Use point (0, 3000).
3000 = -687.5(0) + b
b = 3000
The equation is
y = -687.5x + 3000
Since we are using points (t, v) instead of (x, y), we have:
v = -687.5t + 3000
Answer: d. v = -687.50 t + 3,000
10 more people are on the bus after the second stop, compared to the first.
