7th Grade Math

Lesson 1B Rates and Functions 381

11. INSECTS A cricket will chirp 35 times per minute when the outside
    temperature is 72°F.
    a. Write an equation using two variables to show the relationship
    between the total number of times a cricket will chirp t after
    m minutes at this temperature.
    b. Use your equation to explain how to find the number of times a
    cricket will have chirped after 15 minutes. Then solve.

Copy and complete each function table. Then identify the domain

and range.

12. y = 0.5x 13. y = 1.3x
    x 0.5xy
    1
    2
    3
    4

(^) x 1.3xy
1
2
3
4

14. y = - 0.2x 15. y = _^23 x

x -0.2xy

0

1

2

3

(^) x _^2
3 xy
2
3
4
5

16. MEASUREMENT The formula for the area of a rectangle with a length of
    6 units and width w is A = 6 w.
    a. Make a function table that shows the area in square units of a
    rectangle with a width of 2, 3, 4, and 5 units.
    b. Study the pattern in your table. Explain how the area of a rectangle
    with a length of 6 units changes when the width is increased by 1 unit.

1717 SCIENCE The table shows the approximate

velocity of certain planets as they orbit

the Sun.

Orbital Velocity Around Sun

Planet Velocity (mi /s)

Mercury 30

Earth 19

Jupiter 8

Saturn 6

Neptune 5

a. Write an equation to show the relationship

between the total number of miles m Jupiter

travels in s seconds as it orbits the Sun.

b. What equation can be used to show the

total number of miles m Earth travels in

s seconds?

c. Use your equation to explain how to find the number of miles Jupiter

and Earth each travel in 1 minute. Then solve.

18. RUNNING The average marathon running speed is 5.5 miles per hour.
    Find the number of miles run after 1, 2, 3, and 4 hours at this rate.

B

Real-World Link

Crickets are among

the 800,000 different

types of insects in

the world.

RR

C

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