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- 269
- à 4.4ïUsing Proportions to Solve Word Problems.
- äè Please use Proportions to Solve the following Word
- êêïProblems.
-
- âèIf 3 cups of flour will make 2 loaves of bread, how many cups
- will be needed for 6 loaves?
- êêêêêêè3∙6ï=ï2∙x
- ï3 cupsêx cupsê 3ëxêè18ï=ï2∙xë x = 9 cups
- # ────────ï=ï────────ï,è ─ï=ï─è,ë 18êè ,
- # 2 loavesë6 loavesê2ë6êè──ï=ïx
- êêêêêêë2
-
- éS "If 3 cups of flour will make 2 loaves of bread, how many cups
- will be needed for 6 loaves?"
-
- è To solve this problem using a proportion, you should first set two
- Rates equal to each other to form an equation.
- êêêè3 cupsêè x cups
- #êêêï────────è =è ────────
- êêêï2 loavesêï6 loaves
-
- Note that the units on top and bottom of each side of the equation
- agree.ï"cups" is on top and "loaves" is on the bottom on both sides.
- It is necessary that the units agree on both sides.ïOnce you have
- determined that this agreement exists, then just drop the units.
- êêêêè3êx
- #êêêêè─è=è─
- êêêêè2ê6
-
- Next, you should solve the proportion by cross multiplying.
- êêêê 3∙6è=è2∙x
- êêêêï18è=è2∙x
- êêêê18/2è=èx
- êêêêè9è=èx
-
- Finally, the unit is placed with the answer.è xï=ï9 cups of flour.
-
- This problem could also have been solved by setting two Ratios equal
- to each other.
- êêêè 3 cupsêï2 loaves
- #êêêè ──────è =è ────────
- êêêè x cupsêï6 loaves
-
- ë3ê2
- #ë─è=è─è,è 3∙6è=è2∙xè ,è 18è=è2∙xï,ïx = 9 cups
- ëxê6
-
-
- ï1
- êëIf 2 gallons of paint will cover 3 rooms, how many gallons
- êëwill it take to cover 12 rooms?
-
-
- ë A)ï10 gal.ë B)ï8 gal.êC)ï9 gal.êD)ïå
-
- ü
- êêê 2 gallonsêïx gallons
- #êêê ─────────è =è ─────────
- êêêï3 roomsêè12 rooms
-
- êêêêï2êèx
- #êêêêï─è =è ──
- êêêêï3êï12
-
- êêêê 2∙12ï=ï3∙x
-
- êêêê 24/3ï=ïx
-
- êêêë 8 gallonsï=ïx
- Ç B
- ï2
- êëIf two cans of beans cost $.84, how much will 12 cans
- êëcost?
-
-
- ë A)ï$5.04ê B)ï$4.50ê C)ï$3.00ê D)ïå
-
- ü
- êêêè 2 cansêï12 cans
- #êêêè ──────è =è ───────
- êêêë$.84êë x
-
- êêêêï2êï12
- #êêêê ──è =è ──
- êêêê.84êèx
-
- êêêêï2∙xï=ï.84∙12
-
- êêêêè xï=ï(10.08)/2
-
- êêêêè xï=ï$5.04
- Ç A
- ï3
- êëIf you drive 300 miles on 10 gal., how far can you drive
- êëon 14 gal.?
-
-
- ë A)ï380 milesè B)ï390 milesè C)ï420 milesè D)ïå
-
- ü
- êêê 300 milesêïx miles
- #êêê ─────────è =è ───────
- êêêï10 gal.êè 14 gal.
-
- êêêê300êèx
- #êêêê───è =è ──
- êêêê 10êï14
-
- êêêë 300∙14ï=ï10∙x
-
- êêêë4200/10ï=ïx
-
- êêêè420 milesï=ïx
- Ç C
- ï4
- êëIf 3 inches on a map is 26 miles, how many miles is
- êë12 inches?
-
-
- êA)ï134 milesè B)ï126 milesè C)ï104 milesè D)ïå
-
- ü
- êêêï3 inchesêï12 inches
- #êêêï────────è =è ─────────
- êêêï26 milesêè x miles
-
- êêêêï3êï12
- #êêêê ──è =è ──
- êêêê 26êèx
-
- êêêêï3∙xï=ï12∙26
-
- êêêêè xï=ï312/3
-
- êêêêè xï=ï104 miles
- Ç C
- ï5
- êëIf you can make 20 parts in 4 hours, how many parts can
- êëyou make in 12 hours?
-
-
- êA)ï60 partsëB)ï55 partsëC)ï65 partsëD)ïå
-
- ü
- êêêï20 partsêèx parts
- #êêêï────────è =è ─────────
- êêêï4 hoursêè12 hours
-
- êêêê 20êèx
- #êêêê ──è =è ──
- êêêêï4êï12
-
- êêêê20∙12ï=ï4∙x
-
- êêêê240/4ï=ïx
-
- êêêè 60 partsï=ïx
- Ç A
- ï6
- êëIf a 6 foot pole has a 3 foot shadow, how tall is a tree
- êëwith a 20 foot shadow?
-
-
- ê A)ï35 ft.êB)ï40 ft.êC)ï38 ft.êD)ïå
-
- ü
- êêê6 ft. poleêïx ft. tree
- #êêë────────────è =è ─────────────
- êêë3 ft. shadowêï20 ft. shadow
-
- êêêêï6êèx
- #êêêêï─è =è ──
- êêêêï3êï20
-
- êêêê 6∙20ï=ï3∙x
-
- êêêê120/3ï=ïx
-
- êêêë 40 ft.ï=ïx
- Ç B
- ï7
- êëIf 1 bag of lime covers 100 square feet, how many bags are
- êëneeded to cover 1200 square feet?
-
-
- êA)ï12 bagsë B)ï14 bagsë C)ï16 bagsë D)ïå
-
- ü
- êêêï1 bagêê x bags
- #êêë ───────────è =è ────────────
- êêë 100 sq. ft.êï1200 sq. ft.
-
- êêêê 1êè x
- #êêêê───è =è ────
- êêêê100êï1200
-
- êêêë 1∙1200ï=ï100∙x
-
- êêêè 1200/100ï=ïx
-
- êêêë12 bagsï=ïx
- Ç A
- ï8
- êëIf 3 miles is equal to 4.8 km., how many km. is
- êë20 miles?
-
-
- êA)ï28.6 km.ëB)ï32 km.êC)ï34.4 km.ëD)ïå
-
- ü
- êêêè 3 mi.êè20 mi.
- #êêêè───────è =è ──────
- êêêè4.8 km.êïx km.
-
- êêêê 3êè20
- #êêêê───è =è ──
- êêêê4.8êèx
-
- êêêêï3∙xï=ï4.8∙20
-
- êêêêè xï=ï96/3
-
- êêêêè xï=ï32 km.
- Ç B
- ï9
- êëIf 2 oz. of medicine is 1 dose, how many oz. is
- êë12 doses?
-
-
- êA)ï16 oz.êB)ï18 oz.êC)ï24 oz.êD)ïå
-
- ü
- êêêë2 oz.êèx oz.
- #êêêè ──────è =è ────────
- êêêè 1 doseêï12 doses
-
- êêêêï2êèx
- #êêêêï─è =è ──
- êêêêï1êï12
-
- êêêê 2∙12ï=ï1∙x
-
- êêêê 24/1ï=ïx
-
- êêêë 24 oz.ï=ïx
- Ç C
- ï10
- êëIf an investment of $4,000 earns $580, how much will $20,000
- êëearn?
-
-
- êA)ï$2,900êB)ï$1,800êC)ï$1,700êD)ïå
-
- ü
- êêêè $4,000êï$20,000
- #êêêè ──────è =è ───────
- êêêë$580êë$x
-
- êêêë4,000êï20,000
- #êêêë─────è =è ──────
- êêêê580êè x
-
- êêêë4,000∙xï=ï580∙20,000
-
- êêêêè xï=ï11,600,000/4,000
-
- êêêêè xï=ï$2,900
- Ç A
-
-