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Old 07-24-2007   #1
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Default can you solve this math problems???

1. Two hours after a truck leaves Phoenix traveling at 45 miles per hour, a car leaves to overtake the truck. If it takes the car ten hours to catch the truck, what was the speed of the car?2. A 20 gallon salt solution is 30% salt. What is the greatest number of gallons of water that can be evaporated so the solution is still less than 45% salt?pls. answer this.....
Old 07-24-2007   #2
cassandras_evil_sister 1
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the car had to go 54 mph to catch the truck .2hrs x 45 mph =90+ 10 hrs x 45 mph for the truck and car to meet=54 mph or another way to say it, truck traveled 540 miles in 12 hrs time, 10x 45+90=540, the car went 54 mph to catch it, if the truck never stopped and both left the same point 2 hrs apart.about the solution q, i dont know
Old 07-24-2007   #3
jeetu N
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ans for 2:water(gallons) salt 20 30x 44x=600/44=13.63gallonsgallons of evaporated water =20-13.63 = 6.37gallons
Old 07-24-2007   #4
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1.the car catches the bus 10 hrs after it (the car) leaves i.e. 12 hrs after the bus leaves phoenix. in 12 hrs, the bus travels a distance 540 miles (45miles/hr*12hrs). that means the car travels 540 miles in 10 hrs. therefore, its speed is 540/10=54miles/hr.2.the salt is 30% in 20 gallons. i.e. it is [(30/100)*20] gallons.it comes out to be 6 gallons. for it to be 45%, [(45/100)*x]=6 gallons. where x is the total amount of solution left after evaporating. on calculating, x comes out as 13.33. hence, amount of water that can be evaporated so as to keep the solution less than 45% is less than 6.66 gallons
Old 07-24-2007   #5
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30%*20= 6 gallons saltsalt-----= %salttotal6/x=45% (.45)x=6/.4513.3333333so 13.33333 gallons of water will be 45% saltso you could evaporate 6.666666 gallons of water

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