7th Grade Math

274 Proportions and Similarity

= Step-by-Step Solutions begin on page R1.

Extra Practice begins on page EP2.

For Exercises 5–12, explain your reasoning.

Examples 1 and 2 5. RECREATION The Vista Marina rents boats for $25 per hour. In addition to

the rental fee, there is a $12 charge for fuel. Is the number of hours you

can rent the boat proportional to the total cost? Explain.

6. ELEVATORS An elevator ascends, or goes up, at a rate of 750 feet per
   minute. Is the height to which the elevator ascends proportional to the
   number of minutes it takes to get there? Justify your response.


7. PLANTS A vine grows 7.5 feet every 5 days. Is the length of the vine on
   the last day proportional to the number of days of growth? Explain.


8. TEMPERATURE To convert a temperature in degrees Celsius to degrees
   Fahrenheit, multiply the Celsius temperature by _^9
   5
   and then add 32°. Is a
   temperature in degrees Celsius proportional to its equivalent
   temperature in degrees Fahrenheit? Explain your reasoning.


9. ADVERTISING On Saturday, Querida gave away 416 coupons for a free
   appetizer at a local restaurant. The next day, she gave away about
   52 coupons an hour.
   a. Is the number of coupons Querida gave away on Sunday proportional
   to the number of hours she worked that day? Explain.
   b. Is the total number of coupons Querida gave away on Saturday and
   Sunday proportional to the number of hours she worked on Sunday?
   Justify your response.


10. TAXES MegaMart collects a sales tax equal to _^1
    16
    of the retail price of each
    purchase and sends this money to the state government.
    a. Is the amount of tax collected proportional to the cost of an item
    before tax is added?
    b. Is the amount of tax collected proportional to the cost of an item after
    tax has been added?

1111 MEASUREMENT Determine whether the measures for

s

the figure shown are proportional.

a. the length of a side and the perimeter

b. the length of a side and the area

12. RIDES The table shows the fee Number of
    Ride Tickets 5 10152025
    Fee ($) 5 9.50 13.50 16 18.75

for ride tickets at a carnival.

a. Is the fee for ride tickets

proportional to the number

of tickets? Explain your reasoning.

b. Can you determine the fee for 30 ride tickets?

Real-World Link

Ascending at a speed

of 1,000 feet per

minute, the five

outside elevators of

the Westin St. Francis

are the fastest glass

elevators in San

Francisco.

RR

A

B

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