math problem?

Question

distance problem

a) two cars leave a hotel at the same time and travel in opposite directions. if one car travels at a rate of 45 kph and the other at 40 kph, how long will it take them to be 385 kilomteres apart?

* i can't seem to understand the problem. kindly give me the equation. thanks so much.

oh btw, if u dont know the answer..then dont answer. =) just a thought.

Answer 1

The cars are moving away from each other because they they are moving in opposite directions.
The distance between them in 1 hour would be 45+40 km=85 km
so to be 385 km apart,they would take 385/85=77/179after reducing)or4 9/17 hours.

Answer 2

Suppose they start from A. C1 and C2 are two cars. C1 at 45kmph, C2 at 40kmph
C2<<<<<<<<<<< A >>>>>>>>>>>>C1

After one hour,
C1 goes 45 kms from A and
C2 goes 40 kms from A
So both are away from each other by 85 kms. every hour.

So in 4 hours their distance becomes
85*4= 340 kms

After another 30 minutes, C1 takes another 22.5 kms. while C2 takes another 20 kms. (42.5 kms. in total)
After 4 hours 30 minutes, they have travelled
85*4 + 42.5 = 382.5 kms.

So they will take little more than 4 1/2 hrs to be 385 kms distant from each other. I am forgettin the exact way to solve it.

Answer 3

not a 100% on this. If I'm correct it would be 4.53 hours. If they make 85kilometres per hour (40+45) then you should divide this into 385 to get your total number of hours.

Another example, 2 cars at 50kph opposite directions, how long for 200kilometres would be 2 hours as they make 100kph between them.

Answer 4

In one hour they will be 85 miles apart, 2 hours 170 and so on. At 4 1/2 hours they will be 382 1/2 miles apart, so a minute or two more and they will be 385...............

Answer 5

45*t1 = d1 40 *t2=d2 t1=t2 d2=385 -d1 40t2=385-45t2 85t2=385 385/85= 4.59 hours