word problems

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kathy's

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Bradon and pat drove from Edmonton to saskatoon a distance of 545 Km. Brandon drove the first part of the trip @ n average spped of 100 Km/h, and pat drove the remainder at an average of 90km/h. If the trip took brando and pat 5.74 hours dtermine the number of hours each drove.

I am not sure how to do this bu if i am wrong can someoe help me?

k would you go like this:
90x+ 100y= 545
x+y= 5.75 h
wold that be the formula? am i doing this right?
 
It looks like you're using "x" to mean "the time, in hours, driven by Brandon at 90 kph" and "y" to mean "the time, in hours, driven by Pat at 100 kph". If so, then the standard "uniform rate" equation, "d = rt" (for "distance is equal to the rate times the time") gives:

. . . . .Brandon:
. . . . . . .rate: 90
. . . . . . .time: x
. . . . . . .distance: 90x

. . . . .Pat:
. . . . . . .rate: 100
. . . . . . .time: y
. . . . . . .distance: 100y

. . . . .totals:
. . . . . . .time: x + y = 5.75
. . . . . . .distance: 90x + 100y = 545

So your formulation is correct. Now you need to solve the system of equations.

Eliz.
 
Add: "Let x be the time of Pat's travel, in hours, and let y be the time of Brandon's travel, in hours."

Then you're good to solve the simultaneous equations for x and y.
 
Exactly right.
My only criticism is that it would be better to use b & p instead of x & y. That way when tou get to the end you still know which is which.
 
Gene said:
...it would be better to use b & p instead of x & y.
Click to expand...
"Better" in that using these letters would make it much easier to remember, once the system is solved, what the letters stand for. In other words, either label, or else use helpful letters, or both.

Because -- trust me -- it's very frustrating to spend fifteen minutes on the test figuring out what "x" is, only to have forgotten by then just what the heck "x" had stood for. :shock:

Eliz.
 
Thanks ppl but i have one more question you know how you guys put down
90x + 100y= 54 5.. i don't know how to solve that... so yeah can you ppl give me an exaple not this one cuz then you will give me the answere by any chance?
thanks I would really appreaciate it :D
 
You don't solve one equation at a time. You solve them together, as a "system".

What method(s) have you learned for solving systems?

Eliz.
 
um.. okay so i have learned elimination method .. is that the one I use?
 
Ok; an example using the same actors!

Distance: 300
Brandon speed: 50
Pat speed: 40
Total time: 7 hours

b = distance by Brandon; then distance by Pat = 300 - b

speed = distance / time; so time = distance / speed

7 = b/50 + (300-b)/40
multiply by LCD of 50 and 40 which is 200:
1400 = 4b + 5(300-b)
4b + 1500 - 5b = 1400
b = 100

So Brandon drove 100 miles: 100/50 = 2 hours
and Pat drove 300-100 = 200 miles: 200/40 = 5 hours

Can you follow all that?
 
thanks yes it did help me i got Brandron drove for 2.75 hours and Pat drove 3 hours, is that right?
you guys rock!!! thanks for your help
 
kathy's said:
thanks yes it did help me i got Brandron drove for 2.75 hours and Pat drove 3 hours, is that right?
you guys rock!!! thanks for your help
Click to expand...
Good job; you can check your own answers this way:
Brandon: 2.75 @ 100 = 275 miles
Pat: 3 @ 90 = 270 miles
275 + 270 = 545 : capish?
 
Good job.
I hope you multiplied your second equation by 100 then subtracted your first equation from that. That would be the easiest way to eliminate y. No matter how you did it, you got it!
------------------
Gene
 
Im being pulled out of school if i dont do my homework and bring my grade upi from a 52 to passing, so Id really Love help.

Its simple (To you guys b/c your older,wiser, and not dumb like me)

Ive been in gifted math for 3 years and ive failed it 3 years Wanna help?


1)Lynn wants to be at school at 7:30 am.It takes her 3/4 hr. to get dressed, 1/2 hr. to eat breakfast and 15 minutes to walk to school. what time should she get up?

2)John bought a pair of shoes during a 1/4 off sale.The original price was 34$.
After he paid for the shoes he had $14.26.How much money did he start with?

3)You are an employee at a store thats is having a 1/3 off sale.
Employees get an additional 1/5 off the sale price.How much would you pay for a jacket that was originally $60?

4)Kimo Has 1 1/2 lb. of salmonhe wants each person to get a 6-oz serving.How many people can he feed?


5)A 17 Min. Phone call to boston costs $2.38.What is the cost per minute?

6)One brand of cereal costs $1.79 for a 7.2 oz. box. A larger box that weighs 1 lb 4.25 oz costs $3.69 which size box is the better buy?

7)Eighteen students in a class of 25 students plan to go on a class hiking trip. What percent of the students plan to go on the trip?

8.)In 1996 Voters elected 79 new members to the house of represenatives. The total number of representataives is 435.What percent were new?

9)A T-shirt store bought 5 dozen shirts for $4.29 each. The store owner Decided to sell the shirts for $6.59 Each.What was the percent of increase in the shirts?

10)The scale on a map is 1.5 In:500 miles The map distance from chicago to tokyo is 12 in. find the actual distance between the cities.
 
First, don't hijack somebody else's thread.
Second, this is not a hw service, so what have you done on these problems?
 
Forever_Failing_Math said:
5)A 17 Min. Phone call to boston costs $2.38.What is the cost per minute?
Click to expand...
You're in "gifted math" and you can't divide 2.38 by 17?
Who are you trying to kid?
 
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