Lan found a cd player on sale. the original price was $59.95. sales tax is 5.5 percent. if the cd player was on sale for 15 percent off the original price, how much would lan pay, including sales tax?
(b) one week later the price of the cd player was further reduced by an additional 10 percent, how much would lan pay including sales tax?

(A) Lan should pay $53.79 including sales tax

(B) Lan would now pay $48.41 for the CD player

Step-by-step explanation:

Percentages

Think of a certain product that has a price P. To increase its price a percentage x, we calculate the increase as

Then we add the increase to the original price to get

The same applies when the price is decreased by an x%

(A) The original price of a CD player was $59.95 and it was on sale for 15% off the price. The new price is

Now we must add the 5.5% sales tax

Lan should pay $53.79 including sales tax

(B) One week later, the CD player was reduced by another 10%. The new price was

Plus the tax

Lan would now pay $48.41 for the CD player

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 is 17