A sample of a radioactive isotope had an initial mass of 620 mg in the year 2003 and decays exponentially over time. A measurement in the year 2005 found that the sample's mass had decayed to 390 mg. What would be the expected mass of the sample in the year 2010, to the nearest whole number?

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.

the radius is 2 times the diameter.

step-by-step explanation:

final total: 63

step-by-step explanation:

60 times sales tax

60 times 0.05

3

60 + 3

63