Help me figure out this math problem...

[JohnCU]

Just had this question on a test, I think I got it right, but I'm not sure:

A private jet leaves Midway airport at 180km/h. Two hours later, airplane #2 leaves the same airport at 900km/h. How far from the airport will airplane #2 be when it overtakes the private jet?

I got 36km.

 

[CPA]

I got 450 KM.

Breaking it down in km/minutes.

0+(15x) = 360 + (3x)
12x = 360
x = 30


360 + (3 * 30) = 450.

 

[Viper GTS]

Presuming they are actually headed the same direction...

360 + 180x = 900x

Solve for x, that will give you the elapsed time (from x = 0 when the 2nd plane leaves) they meet.

Multiply the time by the speed of the second jet to get your distance.

450km is correct, you know 36km can't be correct because plane #1 is already 360km away when the 2nd plane leaves.

Viper GTS

 

[CPA]

Originally posted by: Viper GTS
Presuming they are actually headed the same direction...

360 + 180x = 900x

Solve for x, that will give you the elapsed time (from x = 0 when the 2nd plane leaves) they meet.

Multiply the time by the speed of the second jet to get your distance.

Viper GTS

Viper, I think your formula is enough for the distance, you shouldn't have to multiply by the speed of the second jet.

 

[JohnCU]

Ah thanks guys, I guess my brain slipped for a second..

 

[Viper GTS]

Originally posted by: CPA

Originally posted by: Viper GTS
Presuming they are actually headed the same direction...

360 + 180x = 900x

Solve for x, that will give you the elapsed time (from x = 0 when the 2nd plane leaves) they meet.

Multiply the time by the speed of the second jet to get your distance.

Viper GTS

Viper, I think your formula is enough for the distance, you shouldn't have to multiply by the speed of the second jet.

Solve for x, you'll get 0.5.



Viper GTS

 

[CPA]

Originally posted by: Viper GTS

Originally posted by: CPA

Originally posted by: Viper GTS
Presuming they are actually headed the same direction...

360 + 180x = 900x

Solve for x, that will give you the elapsed time (from x = 0 when the 2nd plane leaves) they meet.

Multiply the time by the speed of the second jet to get your distance.

Viper GTS

Viper, I think your formula is enough for the distance, you shouldn't have to multiply by the speed of the second jet.

Solve for x, you'll get 0.5.



Viper GTS

Correct, I think I took it the next step forward, which was actually what you were stating, but I confused. My bad.