Six hundred adult Americans were asked by telephone poll, "What do you think constitutes a middle-class income?" Also, include the left endpoint but not the right endpoint. Salary ($)Relative Frequency
< 20,000.02
20,000–25,000.09
25,000–30,000.19
30,000–40,000.26
40,000–50,000.18
50,000–75,000.17
75,000–99,999.02
100,000+.01

What percentage of the survey answered "not sure"?
What percentage think that middle class is from $25,000 to $50,000?
Find the 40th and 80th percentiles.
40th percentile = Between $ and $
80th percentile = Between $ and $

50.6

step-by-step explanation:

7.3

step-by-step explanation:

the answer is 99.

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.