For several years, Graham has gathered data on students who own a computer and on their performance on a typing-speed test. He creates the linear model y = 3.8x + 17.4 where y represents the typing speed, in words per minute, of a student and x represents the number of years the student has owned a computer. According to Graham’s model, what is the approximate speed of a student who has owned a computer for three years? 21 words/min 29 words/min 56 words/min 64 words/min

min 64 words.

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.

answer: both chords and diameters have two endpoints on a circle. diameters must intersect the center of a circle.