Algebra 1 Common Core Student Edition, Grade 8-9

t

Got It? 3. a. A building is 1450 ft tall. How m any m eters tall is th e building? Use the

fact th a t l m ~ 3.28 ft.

b. M onetary exchange rates change from day to day. On a particu lar day, the

exchange rate for dollars to euros was ab o u t 1 dollar = 0.63 euro. About

how m any euros could you get for $325 on th a t day?

You can also convert rates. For example, you can convert a speed in m iles p er h o u r

to feet p er second. B ecause rates com pare m easures in two different units, you m ust

m ultiply by two conversion factors to change b o th of th e units.

Converting Rates

A student ran the 50-yd dash in 5.8 s. At what speed did the student run in

miles per hour? Round your answer to the nearest tenth.

The ru n n in g speed in yards

per second

Need

The ru n n in g speed in

miles per hour

i:; ic a n ,

Write the speed as a ratio. Choose

conversion factors so th a t the original

units (yards and seconds) divide out,

leaving you w ith the units you need

(miles and hours).

5 0 y d 1 m i

5.8^r ' 1760 y d

180,000 m i

3600^

lh

17.6 m i/h Simplify.

Divide common units.

10,208 h

The stu d en t ran at a speed of ab o u t 17.6 m i/h.

Got It? 4. a. An athlete ran a sprint of 100 ft in 3.1 s. At w hat speed was th e athlete

ru n n in g in m iles p e r hour? R ound to th e n ea rest m ile p e r hour,

b. Reasoning In Problem 4, one stu d en t m ultiplied by th e conversion

factors1760 y d ' 1 m in 1 m i

Why or why not?

60 s , an d 601™n to find th e speed. Can this m eth o d work?

118 Ch ap t er 2 So l v i n g Eq u a t i o n s