C4 Math Problem
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Originally Posted by Bilyk
wtf?
the lincoln is doing 1mile/45 sec
which is 1.333333... miles / minute
which is 80 miles / hour
why would it be 90?!?!
the lincoln is doing 1mile/45 sec
which is 1.333333... miles / minute
which is 80 miles / hour
why would it be 90?!?!
1.333333miles/min X 60min/hr = 79.99998 miles/hrYou are wrong sir! No 'rounding off' on this forum! no way...
Instructor
Joined: Aug 2004
Posts: 108
Likes: 0
Originally Posted by VFR750
Actually, he can't do it. If it's a 1 mile track, it took him 2 minutes to go around it at 30 MPH. To average 60 for both laps he would have to take 2 minutes total. He's out of time! Sorry, kind of a trick question. 
Drifting
Joined: Sep 2004
Posts: 1,638
Likes: 3
Originally Posted by vetteweiser
I was thinking it would be 90. So why is it 80?
So if you drove at that speed for 1 minute you would cover 1 1/3 miles per minute
and 1.3333 miles /minute X 60 minutes / hour = 79.99 miles /hour(rounding error)
Safety Car
Joined: Apr 2003
Posts: 3,793
Likes: 9
From: VA
Originally Posted by VFR750
Actually, he can't do it. If it's a 1 mile track, it took him 2 minutes to go around it at 30 MPH. To average 60 for both laps he would have to take 2 minutes total. He's out of time! Sorry, kind of a trick question.
Instructor
Joined: Aug 2004
Posts: 108
Likes: 0
Originally Posted by steve9899
That would have worked, if you'd stated it was a 1 mile track. But you didn't.
This result is actually independent of track length. The equations for his problem are (correct me if I'm wrong...)
60t = 30t1 + V*t2 (1)
60t = 60t1 (2)
t = t1 + t2 (3)
(2) -> t = t1, put this result in (3) and t2=0... assuming track length > 0 then t2 has to be greater than zero. In other words, no matter how fast you second lap is the total average speed will be less than 60 mph.
Le Mans Master
Joined: Dec 2002
Posts: 6,715
Likes: 2
From: Santa Teresa New Mexico
Originally Posted by Nathan Plemons
This was in the newspaper this morning and a little bit of an *** kicker. The problem is easy to solve after you think about it but the obvious answer that you want to say at first is incorrect.
If your ricer is traveling 60 MPH it takes 1 minute to travel 1 mile.
If your Corvette is traveling 120 MPH it takes 30 seconds to travel 1 mile.
How fast must your Lincoln be going to travel the mile in exactly 45 seconds?
If your ricer is traveling 60 MPH it takes 1 minute to travel 1 mile.
If your Corvette is traveling 120 MPH it takes 30 seconds to travel 1 mile.
How fast must your Lincoln be going to travel the mile in exactly 45 seconds?
Lincoln Town Car or Navigator?
How far can a Lincoln travel at 80 mph in 45 seconds?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
Thread Starter
Race Director
Joined: May 2001
Posts: 14,165
Likes: 9
Uh, for you guys who say it's 79.99999... You are the ones introducing the rounding error. Leave it as a fraction and it works perfectly.
.33333 is simply a representation of 1/3. By truncating it at all you are introducing the error. Fractions are always more accurate.
.33333 is simply a representation of 1/3. By truncating it at all you are introducing the error. Fractions are always more accurate.
Team Owner
Joined: May 2002
Posts: 24,337
Likes: 25
From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Quiz #2:
A Corvette driver goes around a city block. On the first side, he goes 10mph... turns, goes 20mph. Goes 30 mph on the third side, then 40 mph, when he reaches his starting point.
What is his average speed?
19.2 mph
A Corvette driver goes around a city block. On the first side, he goes 10mph... turns, goes 20mph. Goes 30 mph on the third side, then 40 mph, when he reaches his starting point.
What is his average speed?
19.2 mph
Last edited by CentralCoaster; Jan 16, 2005 at 10:27 PM.
Advanced
Joined: Sep 2004
Posts: 92
Likes: 0
From: Columbia Missouri
Originally Posted by CentralCoaster
Quiz #2:
A Corvette driver goes around a city block. On the first side, he goes 10mph... turns, goes 20mph. Goes 30 mph on the third side, then 40 mph, when he reaches his starting point.
What is his average speed?
19.2 mph
A Corvette driver goes around a city block. On the first side, he goes 10mph... turns, goes 20mph. Goes 30 mph on the third side, then 40 mph, when he reaches his starting point.
What is his average speed?
19.2 mph
Instructor
Joined: Sep 2003
Posts: 118
Likes: 0
From: Sanborn NY
algebra class
damm i am going to print this and post it for my algebra classes
these kids today need to see why you need math
i will have to tell them they can't drive fast cars unless they know what a 45 sec between mile posts translates too
these kids today need to see why you need math
i will have to tell them they can't drive fast cars unless they know what a 45 sec between mile posts translates too
Safety Car
Joined: Aug 2004
Posts: 4,907
Likes: 731
From: Southwest Kansas
2022 Corvette of the Year Finalist -- Unmodified
2021 C6 of the Year Winner - Unmodified
Originally Posted by deiaggie
alot of you guys are trying way too hard on this one...
there are 3600 seconds on an hour (60*60) all you need to do is divide 3600 by the amount of seconds you want to do the mile in and you get how many miles you will do in one hour or MPH
3600/45 seconds=80 MPH
3600/60 seconds=60 MPH
3600/30 seconds=120 MPH
3600/40 seconds=90 MPH
3600/51 seconds = 70.5 MPH
3600/48 seconds = 75 MPH
It works and I have yet to get a ticket when I stay within the 5 mph buffer that the KHP (unofficially) gives you.
Racer
Joined: Dec 2004
Posts: 429
Likes: 0
From: Midddleburg FL
Originally Posted by Nathan Plemons
Ok, here's the logic, set it up as a fraction.
60 MPH / 60 Seconds vs 120 MPH / 30 Seconds
Well you think that 45 seconds is half way between 30 and 60, 90 mph is half way between 60 and 120, must be right huh?
Unfortunately that's not the case.
To go from 60 to 120 you double it. To go from 60 to 30 you take half of it. Hmm, see the pattern? Anything you do to the top you have to take the INVERSE of on the bottom and vice versa. So 45 seconds is 3/4 of 60 seconds. This means you have to multipy the top by 4/3. 60*(4/3) = 80
Annyoying huh? My dad and I both said 90 first too. He's a math major from way back. He figured it out in another way, which basically accomplishes the same thing.
60 MPH / 60 Seconds vs 120 MPH / 30 Seconds
Well you think that 45 seconds is half way between 30 and 60, 90 mph is half way between 60 and 120, must be right huh?
Unfortunately that's not the case.
To go from 60 to 120 you double it. To go from 60 to 30 you take half of it. Hmm, see the pattern? Anything you do to the top you have to take the INVERSE of on the bottom and vice versa. So 45 seconds is 3/4 of 60 seconds. This means you have to multipy the top by 4/3. 60*(4/3) = 80
Annyoying huh? My dad and I both said 90 first too. He's a math major from way back. He figured it out in another way, which basically accomplishes the same thing.
Melting Slicks
Joined: May 2004
Posts: 2,286
Likes: 2
From: Stamping Ground KY
Originally Posted by VFR750
A driver runs 30 MPH for his first lap (in his MG I guess). How fast does he have to go for the second lap to bring his average up to 60 MPH for the two laps? :o
Or is that only for a straight line?