two families are traveling by car to a camp 280 kilometers away. one family leaves 20 minutes ahead of the other family and travels at an average speed of 40 kilometers per hour. what would the speed of the second familys car need to be if the family is to reach the camp the same time as the first family??

Question

phi · Answer

How long does the first family take to go 280 km when traveling at 40 km/h?

anonymous · Answer

thats what you have to solve to find. well one of the things i think.

phi · Answer

Yes it is a good first step.  Do you know speed*time= distance?
If you know speed and distance, you can find time.

anonymous · Answer

but i dont know the rate and time of both cars or families or whatever.

phi · Answer

How long does the first family take to go 280 km when traveling at 40 km/h?

savvy · Answer

42km/hr

anonymous · Answer

alls it tells you is how far ahead the first family is from the second family.

phi · Answer

You have all the information you need to answer
How long does the first family take to go 280 km when traveling at 40 km/h?

you know distance, you know speed.  you know the formula
speed*time= distance
you can find time.

phi · Answer

the first thing to do is replace the words "speed" and "distance" with the numbers to get an equation

anonymous · Answer

7 hours.

phi · Answer

The second family has how much time to get to the camp.  Remember the first family has a head start of 20 minutes  or (1/3 of hour)

phi · Answer

Think like this. Say the first family left at noon.  after 7 hours they will be at the camp at 7 pm
Say the 2nd family leaves at 12:20  and they want to get to the camp at 7 pm
How much time do they have to get there?

anonymous · Answer

6 hours and 40 minutes

anonymous · Answer

sooo... thats where im stuck.

phi · Answer

OK,  you know speed*time= distance
you know time, you know distance
you can find speed.

The only thing is you should make your time  hours  (not hours and minutes)
so 6 hours 40 mins is the same as 6 2/3 hours    (oh oh fractions)
but you can make the time= 20/3 hours  (that is an improper fraction)
Can you do
speed* 20/3 hours = 280
?
multiply both sides by 3/20

anonymous · Answer

42 km/h

phi · Answer

yes.

anonymous · Answer

sooo is that all there is to it??