Brainlies! 1. a fuel is purified by passing it through a clay pipe. each foot of the clay pipe removes a fixed percentage of impurities in the fuel. let f(x) represent the amount of pollutants, in tons, left in the fuel after it had passed through x feet of the clay pipe. f(x) = 10(0.8)^x what does the number 0.8 represent? every foot of the pipe keeps 80% of the pollutant. every foot of the pipe removes 80% of the pollutant. the original amount of pollutant present in the fuel was 80 tons. the original amount of pollutant present in the fuel was 20 tons. 2. choose the equation below that represents the line passing through the point (2, −4) with a slope of one half. y = one halfx + 5 y = one halfx − 3 y = one halfx − 5 y = one halfx + 3

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.