Spiral Review 99

15. Roberto paid $35.75 for dinner at a restaurant, plus an additional $7.15

tip. What percent of the bill did he pay as a tip? Round to the nearest

percent, if necessary.

He paid 17% of the bill as a tip.

Step-by-step explanation:

Paid $35.75 for dinner at a restaurant, plus an additional $7.15 tip.

So in all, he paid 35.75 + 7.15 = $42.9

Tip as a percent:

Tip(7.15) multiplied by 100 and divided by the total(42.9). So

7.15*100/42.9 = 16.7%

Rounded to the nearest percent

He paid 17% of the bill as a tip.

none of the above.

for one of the equations to be used in the process, there has to be a term in the equation since squared is .

since there is only a term in the first equation, we cannot derive a from completing the square.

solving with completing the square

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.