Two groups of students were asked how far they lived from their school. the table below shows the distances in miles

group a (distance in miles) 1 1.5 3.03 3.2 2.8 1.5 1.8 2.5 2.2
group b (distance in miles) 2 2.5 3.23 1.3 1.8 2.4 3 1.5 1.8

which statement best compares the mean distances for the two groups?

it is equal for group a and group b.

it is greater for group b than group a.

its value for group a is double the value for group b.

its value for group b is double the value for group 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.