SOLUTION: These are more about problem solving with equations
7)A jet plane traveling at 500 mph overtakes a propeller plane traveling at 200 mph that had a 2 hour head start. How far from
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7)A jet plane traveling at 500 mph overtakes a propeller plane traveling at 200 mph that had a 2 hour head start. How far from
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Question 71533: These are more about problem solving with equations
7)A jet plane traveling at 500 mph overtakes a propeller plane traveling at 200 mph that had a 2 hour head start. How far from the starting point are the planes?
9) The jones family drove to Disneyland at 50 miles per hour and returned on the same route at 40 mph. Find the distance to Disneyland if the total time was 7.2 hours?
11) How much pure acid should be mixed with 2 gallons of a 40% acid solution in order to get a 70% acid solution?
13)Planters peanuts company wants to mix 20 pounds of peanuts worth $3 a pound with cashews worth $5 a pound in order to make an experimental mix worth $3.50 a pound. How many pounds of cashews should be added to the peanuts? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! 7)A jet plane traveling at 500 mph overtakes a propeller plane traveling at 200 mph that had a 2 hour head start. How far from the starting point are the planes?
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Let d = distance from starting point:
Write a time equation: time = dist/speed
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Props time - Jets time = 2
d/200 - d/500 = 2
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Mult equation by 1000 to get rid of the denominators
5d - 2d = 2000
3d = 2000
d = 2000/3
d = 666.67 miles
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Check:
666.67/200 - 666.67/500 =
3.33 hrs - 1.33 hr = 2 hrs
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9) The jones family drove to Disneyland at 50 miles per hour and returned on the same route at 40 mph. Find the distance to Disneyland if the total time was 7.2 hours?
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Let d = distance to DL
time = dist/speed
there time + return time = 7.2
d/50 + d/40 = 7.2
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Mult eq by 200 to get rid of the denominators
4d + 5d = 200(7.2)
9d = 1440
d = 1440/9
d = 160 mi to DL
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Check:
160/50 + 160/40
3.2 hrs + 4 hrs = 7.2 hrs
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11) How much pure acid should be mixed with 2 gallons of a 40% acid solution in order to get a 70% acid solution?
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Let x = amt of 100% solution
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We know the total will be 2 gal so:
(2-x) = amt of 40% solution
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Write a per cent equation in decimals:
1.00x + .40(2-x) = .70(2)
x = .8 - .4x = 1.4
x - .4x = 1.4 - .8
.6x = .6
x = .6/.6
x = 1 gal, so 1 gal of each solution is required
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Check: 1.0(1) + .4(1) = .7(2)
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13)Planters peanuts company wants to mix 20 pounds of peanuts worth $3 a pound with cashews worth $5 a pound in order to make an experimental mix worth $3.50 a pound. How many pounds of cashews should be added to the peanuts?
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Let x = lbs of cashews
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We know the peanuts are 20 lb, so the resulting mixture will be (20+x)
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3(20) + 5(x) = 3.5(20+x)
60 + 5x = 70 + 3.5x
5x - 3.5x = 70 - 60
1.5x = 10
x = 10/1.5
x = 6.67 lb of cashews required
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Check:
2(20) + 5(6.67) = 3.5(26.67)
60 + 33.35 = 93.35 ~
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How about this? Did it enlighten you somewhat?
