Alex is observing the height of a plant. He finds that the plant is growing according to the equation y=2.5x+5, in which y is the total height of the plant in inches, and x is the number of weeks. What is true about the height of the plant? A. The height is proportional, and the rate is 5 inches per week
B. The height is proportional, and the rate is 2.5 inches per week
C. The height is nonproportional, and the rate is 5 inches per week
D. The height is nonproportional, and the rate is 2.5 inches per week

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.