Answer:
4%
Step-by-step explanation:
A 20% solution with a total volume of 400 mL has 20% * 400 mL of solute.
20% * 400 mL = 80 mL
When you dilute the solution to 2 L, you introduce additional water, but no additional solute, so now you have the same 80 mL of solute in 2 L of total solution.
The concentration is:
(80 mL)/(2 L) = (80 mL)/(2000 mL) = 0.04
As a percent it is:
0.04 * 100% = 4%
Take partial derivatives and set them equal to 0:

We find one critical point within the boundary of the disk at

. The Hessian matrix for this function is

which is positive definite, and incidentally independent of

and

, so

attains a minimum

.
Meanwhile, we can parameterize the boundary by

with

, which gives

with critical points at

At these points, we get


so we attain a maximum only when

, which translates to

.
$2.25x+$3.50=$35
so, $35-$3.50=$31.50
Then you divide $31.50 by $2.25
That equals 14
So, x=14
To solve the problem, get the
percentage of each test by multiplying the score and the percentage then add it all up:
82 * .25 (highest test grade) + 65* .15 (lowest test grade) +
71*.20 (each test remaining) + 77*.20 (each test remaining) + 92*.20 (homework
grade)
= 20.5 + 9.75 + 14.2 + 15.4 + 18.4 = 78.25 or 78% in whole number