distance

eddy2017

eddy2017

Elite Member
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Oct 27, 2017
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Hi, dear teachers and friends:
If Robert drives to an event at an average speed of 45 miles per hour he will arrive an hour late: however if he drives at an average speed of 75 mph he will arrive an hour early. What is the distance that is driving to get to the event?.
As always appreciating no end your helpful hints and help.
eddy
Given
if Robert drives to an event at an average speed of 45 mph he will arrive 1 hour late.
if he drives at 75 mph h will arrive 1 hour early.
d?
 
eddy2017 said:
Hi, dear teachers and friends:
If Robert drives to an event at an average speed of 45 miles per hour he will arrive an hour late: however if he drives at an average speed of 75 mph he will arrive an hour early. What is the distance that is driving to get to the event?.
As always appreciating no end your helpful hints and help.
eddy
Given
if Robert drives to an event at an average speed of 45 mph he will arrive 1 hour late.
if he drives at 75 mph h will arrive 1 hour early.
d?
Click to expand...
Have you done distance/rate/time problems before? Do you know how these values are related?
 
lev888 said:
Have you done distance/rate/time problems before? Do you know how these values are related?
Click to expand...
Yes, I think I have gotten some practice with you here on the forum.
Let me write it out on paper and i'll send it when I am stuck. Thanks, lev.
 
eddy2017 said:
Yes, I think I have gotten some practice with you here on the forum.
Let me write it out on paper and i'll send it when I am stuck. Thanks, lev.
Click to expand...
Sounds good. Next time give it a try first, then post the problem and your solution (see posting guidelines).
 
If you want to mature mathematically you need to try to do your problems on your own. If we keep giving you a hint at each and every stage this will not be as helpful as you trying things on your own.

It is also the policy of this forum that to receive help you need to show your work so we have an idea what hints will help you.

I will start you off by saying that distance = rate * time
 
Jomo said:
If you want to mature mathematically you need to try to do your problems on your own. If we keep giving you a hint at each and every stage this will not be as helpful as you trying things on your own.

It is also the policy of this forum that to receive help you need to show your work so we have an idea what hints will help you.

I will start you off by saying that distance = rate * time
Click to expand...
Thanks jomo. I am working on something. I am going to send it .
 
Given
at 45 mph arrives 1 hour late.
at 75 mph gets there 1 hour early.
let d be distance to the event=?
let t be the time it takes him to get to the event.
so, let the amount of time that is needed to go the distance(d) at 45 mph be t+1, because he arrives 1 h late
let the amount of time that is needed to go the distance(d) at 75 mph be t-1, because he arrives 1 h early.
Is this okay?.
 
eddy2017 said:
Given
at 45 mph arrives 1 hour late.
at 75 mph gets there 1 hour early.
let d be distance to the event=?
let t be the time it takes him to get to the event.
so, let the amount of time that is needed to go the distance(d) at 45 mph be t+1, because he arrives 1 h late
let the amount of time that is needed to go the distance(d) at 75 mph be t-1, because he arrives 1 h early.
Is this okay?.
Click to expand...
If t is the time it takes him to get to the event, then what is this t+1 and t-1 all about. t+1 and t-1 immediately contradicts that t is the time it takes to get to the event.

You need to define t better!
 
Jomo said:
If t is the time it takes him to get to the event, then what is this t+1 and t-1 all about. t+1 and t-1 immediately contradicts that t is the time it takes to get to the event.

You need to define t better!
Click to expand...
Like t is the time that it will take him to get to the event driving at different speeds, so there will be two different t's?.
'cause, i know
d=rt
I have the rates of speed, I need to find the time and the distance, right?.
Can this be set up like this?
d=rt
d=45(t+1) time plus the extra hour it takes him to get there driving at this speed)
d=75(t-1)
time minus the hour it takes him to get there driving at this speed)
d=75(t-1)
Is this good?.
 
d=vt so you are getting there. You said you know velocities and times and we know distances are the same so you can solve for time:

75(t-1)=45(t+1)

Can you solve the above for t?
 
irspow said:
d=vt so you are getting there. You said you know velocities and times and we know distances are the same so you can solve for time:

75(t-1)=45(t+1)

Can you solve the above for t?
Click to expand...
Certainly so.
 
So after you solve for t, just plug that into either of those original distance formulas to find the distance.
 
eddy2017 said:
Certainly so.
Click to expand...
Distance is distance no matter how far you are going, so I can safely say that these two d's are equal to each other
75(t-1)= 45(t+1)
I have to solve for t here,
I'll distribute the speeds in to get rid of the parentheses,
75t-1=45t+45
I'll group like terms
75t-45t-1-45
30t-46
Is this ok so far?. If I ask is because i am not really sure about the next step.
 
eddy2017 said:
Wow, thank you!.
Click to expand...
grouping like terms
75t-45t-75-45
30t-120
I am in doubt as to this grouping of like terms that i did here. Is this the right way to group here?. Just a like will do.
I am asking because if it is good I am getting a negative result.
 
Last edited:
That’s fine what you did there, now isolate and solve for t. To be clear

30t-120=0
 
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