Question

The average, or mean, D, of three exam grades, x, r, and v, is given by the

following formula.
X+r+V
D
3
(a) Solve the formula for v.
(b) Use the formula in part (a) to solve this problem. On your first two exams, your
grades are 85% and 86%: x=85 and r= 86. What must you get on the third exam
to have an average of 90%?
(a) The formula is v= 3D-x-r.
(b) The answer is.

Answer 1

v = 3D - x - r

99%

Step-by-step explanation:

D = (x + r + v)/3

x + r + v = 3D

v = 3D - x - r

(b) When x = 85, r = 86 and D = 90%:

v = 3*90 -85 - 86

= 270 - 171

= 99.

Answer 2

To isolate 'v' in the equation for calculating the mean, rearrange it as 'v = 3D - x - r'. Then, substituting the given values of x, r, and D into this equation, we find that you must score 99% on your third exam to achieve an average of 90%.

Step-by-step explanation:

The given formula represents the calculation of the average (or mean) of three numbers. It's defined mathematically as D = (x + r + v) / 3.

1. To solve the formula for v, we want to isolate v on one side of the equation. So we can rearrange: v = 3D - x - r.

2. Let's substitute x = 85, r = 86, and D = 90 into this formula: v = 3*90 - 85 - 86. Plugging these values into the formula, we get v = 90 - (85 + 86) = 90 - 171 = -81.

   Doing the math, we find that v = 99. This means you must get a 99% to have an overall average of 90%.

Learn more about Rearranging Formulas