Write and Solve a Proportion
TEMPERATURE After 2 hours, the air temperature had risen 7°F.
Write and solve a proportion to find the amount of time it will
take at this rate for the temperature to rise an additional 13°F.
Write a proportion. Let t represent the time in hours.
temperature
time^_^7
2 =^_^13
t^temperature
time
7 · t = 2 · 13 Find the cross products.
7 t = 26 Multiply.
_^77 t = _^267 Divide each side by 7.
t ≈ 3.7 Simplify.
It will take about 3.7 hours to rise an additional 13°F.Solve each proportion.
a. _x
4
= _^9
10
b. _^2
34
= _y^5 c. _^7
3
= _n
2.1Make Predictions
BLOOD During a blood drive, the ratio of Type O donors to
non-Type O donors was 37 : 43. About how many Type O
donors would you expect in a group of 300 donors?
Write the ratio for the given information.
Type O donors
total donors^_^37
37 + 43
or _^37
80
Write a proportion. Let t represent the number of Type O donors.
Type O donors
total donors^_^37
80 =^_t
300Type O donors
total donors
37 · 300 = 80 t Find the cross products.
11,100 = 80 t Multiply.
11,100
_ 80 = _^8080 t Divide each side by 80.t = 138.75 Simplify.
There would be about 139 Type O donors.d. RECYCLING Recycling 2,000 pounds of paper saves about
17 trees. Write and solve a proportion to determine how many
trees you would save by recycling 5,000 pounds of paper.Real-World Link
There are four
different blood types:
A, B, AB, and O.
People with Type O
blood are considered
universal donors.
Their blood can be
transfused into people
with any blood type.RRR
TLesson 1D Proportions 277265_281_C05_L1_895130.indd 277 12/29/09 12:59 PM