Got It? 5. Reasoning If th e gift box’s dim ensions in Problem 5 were m easu red to the
n ea rest h alf inch, how w ould th e greatest possible error be affected?Lesso n Ch eck
Do you kn o w HO W?- Running Last year, an athlete's average tim e to ru n
a mile was 6 m in 13 s. This year, the athlete's average
tim e is 6 m in 5 s. W hat is th e percent decrease? - Cars A used-car dealership buys a car for $2800 and
th e n sells it for $4500. W hat is th e p ercen t increase? - Horses A veterinarian m easures a h orse to be 7.5
ft tall at the shoulder to th e n ea rest half foot. W hat
are the m inim um an d m axim um possible heights of
the horse?
MATHEMATICAL
D o y o u U N D E R S T A N D? PRACTICES- Vo cab ular y D eterm ine w h e th e r each situation
involves a p ercen t increase or a p ercen t decrease.
a. A h at th a t originally costs $12 sold for $9.50.
b. You buy a CD for $10 an d sell it for $ 8.
c. A store buys glasses w holesale for $2 p er glass. The
store sells th em for $4.50. - Reasoning W hat is th e greatest possible error of a
m easu rem en t taken to the n ea rest te n th of a m eter? - W r i t i n g How is calculating p ercen t increase different
from calculating p ercen t decrease?
Pr act i ce an d Pr o b l em - So l v i n g Ex er ci ses
Pr act i ceMATHEMATICAL
PRACTICESTell whether each percent change is an increase or decrease. Then find
the percent change. Round to the nearest percent.- original amount: 12
new amount: 18 - original am ount: 7.5
new am ount: 9.5 - original am ount: 14,500
new am ount: 22,320
8. o r i g i n a l a m o u n t : 9
new amount: 6- original am ount: 40.2
new am ount: 38.6 - original am o u n t: 195.50
new am ount: 215.25
4^ See Problem s 1 and 2.- original amount: 15
new amount: 14 - original am o u n t: 2008
new am ount: 1975 - original am ount: 1325.60
new am o u n t: 1685.60 - Em ploym ent An em ployee was h ired at a w age of $8 p e r hour. After a raise, the
em ployee ea rn ed $8.75 p er hour. W hat was the p ercen t increase? - Clim at e On June 1, 2007, th ere were ab o u t 18.75 h of daylight in Anchorage,
Alaska. On N ovem ber 1, 2007, th ere w ere ab o u t 8.5 h of daylight. W hat was the
percent decrease?
Find the percent error in each estimation. Round to the nearest percent.- You estim ate th at your friend’s little b ro th er is ab o u t 8 years old. He is actually
6.5 years old. - You estim ate th a t your school is ab o u t 45 ft tall. Your school is actually 52 ft tall.
Se e Pr o b l em 3.148 Ch ap t er 2 So l v i n g Eq u a t i o n s