2 planes leave Chicago- one traveling due east and the other due west. The first travels 100 miles faster than the second. How long will it be until they are 2000 mi. apart?
2007-02-21 05:28:53 · 7 answers · asked by gloriousnina 2 in Education & Reference ➔ Homework Help
Let X = the speed of the slower plane
Let Y = the number of hours it takes
X *Y + (X+100)*Y = 2000
Y(X + X + 100) = 2000
Y = 2000/(2X+100)
And that is the answer, 2000 divided by 2 times the slower plane speed plus 100.
2007-02-21 05:47:10 · answer #1 · answered by Anonymous · 0⤊ 1⤋
You don't give sufficient information like what speed either of the planes travels at. Since they are travelling away from each other then, eventually, they will be 2,000 miles apart. Let's assume that we know the speed of the slower plane and it's 200 mph. This means that the other travels at 300 mph.
Speed of travel away from each other is
300 + 200 = 500 mph
It will, therefore take 2000/500 = 4 hours to be 2,000 miles apart
Plane 1 travels at 200 mph so in 4 hours covers 4 X 200 = 800
Plane 2 travels at 300 mph so in 4 hours covers 4 x 300= 1200
1200 + 800 = 2000
Do the same calculation depending on speed for different speeds.
2007-02-21 13:41:19 · answer #2 · answered by quatt47 7 · 0⤊ 1⤋
When you say "100 miles faster," I guess you mean "100 miles per hour faster," otherwise your question wouldn't make sense.
The answer is 20 hours -- because the faster plane is going 100 mph relative to the other plane --so that the situation is just as if the slower plane were standing still and the faster plane was going 100 mph. ... and in that case, you can see that 2000 miles divided by 100 mph = 20 hours.
Please email me if you don't see it, and I'll try to explain it better.
2007-02-21 13:49:33 · answer #3 · answered by yahoohoo 6 · 0⤊ 0⤋
Is their initial speed not provided at all??coz my answer wont help if the speed is unknown. However, assuming the speed of 1st plane to be ' v ' , the speed of 2nd plane wud b ' v+100 ' ,then let the time after which they r 2000 miles apart be ' t ' then t x (100+v) + t x v = 2000 i.e. t (100 + 2v) =2000. So, if u know v ...you can find t and thats the answer. (speed xTime =distance)
2007-02-21 13:48:48 · answer #4 · answered by Curious23 1 · 0⤊ 1⤋
There is no way to figuer out how fast the planes are going.
2007-02-21 13:44:21 · answer #5 · answered by eclipse7500 3 · 0⤊ 1⤋
my algebra teacher said when you have a question like that write a proportion. (it's funny i had a ? like this today for my warm-up / drill)
2007-02-21 13:42:06 · answer #6 · answered by 789512 3 · 0⤊ 1⤋
Hmm... I never liked math...
2007-02-21 13:37:54 · answer #7 · answered by Ieva C 4 · 1⤊ 1⤋