Josephine is taking a college course, and her professor bases the course grade on the average of 2 tests taken in the semester. She wants to know what she needs to earn on the last test to maintain her grade. Rearrange the following equation for b, where C is the average of 2 test scores, a and b. C=a+b/2 Please DO NOT say that this has already been answered, the answer options were different than this question.
Options:
a.) b = 2C/a
b.) b = 2C + a
c.) b = 2C - a
d.) b = 2C(a)

answer: c, the green line

step-by-step explanation:

there is no black line, eliminate b.

simple interest implies periodic payments, but the red line shows no payments, eliminate d.

simple interest has equal payments. if paid say every day, the graph is about a straight line (actually a stairstep).

the yellow line is not straight, eliminate a.

check: the green line is straight, answer is c.

simple interest with positive interest rate gives a straight line sloping up to the right. green line:

g(t) = $100 + ($200-$100) ÷ (20 years) × (t years)

= $100 + (4%/year) × ($100)(t years)

incidentally, the yellow line curving upward represents continuously compounded interest

y = $100 × 2^(t years / (14 assuming the yellow line hits $200 at 14 years. 2^0 is 1, so y(0) = $100; 2^(14/14) is 2, so y(14) = $200.