Miles and Missiles
You are called for the final interview at National Air Force Academy(NAFA). The officer, Sir John Baldwin asks you a single question, which is going to decide your fate.
"Two missiles were shot towards each other. They were 14,600 miles apart when they started. One was moving at 14000 miles per hour and the other at 16000 miles per hour."
"Now listen carefully" he added, "If they collide, that will be the end of the world. You can diffuse them only if you know, how far apart they are one minute before collision. Can you ?"
Sir John paused and added, "Take your time, Sonny."
"If only I had my pencil, paper or calculator." You were thinking.
So, did you passed the test ?
"Two missiles were shot towards each other. They were 14,600 miles apart when they started. One was moving at 14000 miles per hour and the other at 16000 miles per hour."
"Now listen carefully" he added, "If they collide, that will be the end of the world. You can diffuse them only if you know, how far apart they are one minute before collision. Can you ?"
Sir John paused and added, "Take your time, Sonny."
"If only I had my pencil, paper or calculator." You were thinking.
So, did you passed the test ?
Labels: friday special, mathemagic, puzzle
posted by Rajesh Lal at
9:24 AM
51 Comments:
So in 29.13 min, they will collide, so 1 minute before that, they will be 33 mi apart :)
they will colide in 29.2 min., so a minute before that means after 28.2 min., and then they will be 500 miles apart.
i think it would be 2500miles apart, i took the total mph (300,000 ) and divided it by 2 (missles)and divided that by 60 minutes in an hour!
500 miles
In one minute the first missile will travel 16,000/60 and the second missile will have traveled 14,000/60 miles, so if they colide at the end of the minuit they must have been
(14,000+16,000)/60 = 30,000/60 = 500 miles apart.
For Eirc above
How did you calculated without pencil, paper or calculator.
remember you don't have them
I added 14 to 16 and divided by 6 in my head... then put the 0's back in.
Dont know about the people that got 2.9 tho
Sir John, i think you are wrong,
You are not considering the fact taht they are 14600 miles apart
It doest matter how far away there were when they start, thats a bluff. Think about when they collide... a minuite before they would each have 1 minuite left to travel. In one minuite one travles 14,000/60 miles, the other 16,000/60 miles. (MPH/60 = miles per minute). then they mus have been 500 mile away 1 min before colision.
If the 14,600 miles they were apart to start was less than the 500miles, then you would need to take that into account, because the missiles would not be fired one minute before collision, so the distance 1 min before was whereever they started. this is not the case here, so 500 miles is your answer
O i get it now, because how far they travel in a minute, when u add them up, it is 500 ok
This post has been removed by the author.
And By the way, wtf would NAFA shoot off two missiles going toward each other, and if they were test missiles why would they end the world at all?
"Sir" is right, and it's easily done sans calculator. Their combined speed is 30,000MPH which reduces to 500MPM (miles per minute), which is how far they will travel one minute before collision.
I also love how someone asked why our military would do something stupid, like shoot two missles together. Ha! Have you seen the actions of our military lately???
lol, heres a better question, how does knowing the distance between them at t-minus 1 minute help you defuse them?
answer is 500 miles... it's pretty simple...
the speed they are going towards each other is 14000+16000=30000 mph
to get the miles per minute you / by 60 and that gives you 500 miles/min. as you know the distance in a minute is 500 that is the answer.
By the way, 14,000 mph equals about Mach 18. 16,000 mph equals about Mach 21.
answer is 500 doable in your head trivially. NO one proves it's easy in your head, though. here is the proof.
we take 14000 and 16000 and add them. we can ignore the trailing zeroes, and put them back on after the addition, because it's the same number of zeroes.
14(000)+16(000)=30(000)
30000 in 1 hour, or 60 minutes
30000/60
chop off trailing zeroes because this is a ratio.
3000 in 6 minutes
Divide by 3 in head. (easy in this case)
1000 in 2 minutes
Divide by 2 in head. (REALLY easy)
500 in 1 minute
because the distance decreases 500/minute, one minute before collision they are 500 miles apart.
Easy peasy.
Missle A (travelling @ 14000mph)is advancing toward its target at 233.33333 miles a minute. Missle B (travelling @ 16000mph) is closing in on its target at 266.66666 miles a minute.
In a 30 minutes their combined travel would be 15000 miles and each would have missed their mark.
In 29 minutes their combined travel would be just under 14499 miles and they would collide in less than one minute.
Their combined speed is A+B=499.9999 (500) miles/minute. So one minute before collision they would be exactly 500 miles from head-to-head impact.
That moment in time would be sometime just after 28 minutes from initial launch.
You guys are misunderstanding the question...the question is...Did You Pass or Not? And i have no clue what the answer is!! Just thought I might let you know! Bye! Happy New Year!
Regardless of the answer, one thing is for certain, whoever wrote this question certainly didn't pass grammar school!
For the bear who "Eats, Shoots & Leaves "
The best thing you can do is to help fix it and the second best things is to solve it.
Worst thing is to be a cry baby
1st error. You don't know which missle if fired from the east or west. 14,600 miles apart is essentially 1/2 way around the earth. So each missle would be at opposite ends. But the question arises which missle is going with the rotation of the earth, and which missle is going against the rotation of the earth. But in all reality, at the very moment the missles are fired, I have less than one minute before they collide because one missle going at the 14,600 miles I assume is going with the rotation of the earth. The other to compensate with the opposite rotation of the earth must travel faster, thus traveling at 16,000 mph. Therefore we're already dead. In less than one minute each missle will travel 1/4 way around the earth. One going with rotation(Slower missle), the other against rotation (faster). Assuming the 14,600mph one is going with the rotation of the earth.
Ultimately, by the time you asked this question, I have less than a minute before the missles collide. BOOOOOOOOMMMM!!!! We're dead.
I hope your affairs were in order.
This is a good trick question to ask someone. you guys are great.
Supposing Anonymous 7's theory is correct then the only way to not have them collide is to simply not launch them in the first place. And if the question is simply weather i passed, then yes.
P.S. Anonymous 2: You have a very good point there.
You need to know which direction they were they shot: From North and South Or East and West?
You need to know which direction they were they shot: From North and South Or East and West?
Sum the speeds and divide by 60 (1 minute), i think is 500miles
abelynux
They would miss each other because missles travel in the shape of a parabola, and since they are going at different speeds they would travel at different heights and have different lengths causing them to completely miss each other.
14000+16000=30000
30000/60=500 Therefore 500 miles per minute or 500 miles before they meet the last minute.
Why we can do it this way? We can assume that one is static, while the other one is moving with combined speeed.
It would be 500 miles.
This couldn't be earth because it is over 50% of the circumference of 24,901.55 miles at the Equator.
After 12,450.775 miles they would start getting closer again at the equator.
The distance between the two missles changes at a rate of -30,000 miles per hour, or 500 miles per minute, therefore one minute before collision they would be 500 miles apart.
Fardin, it's a joke, lighten up a bit eh? :)
Whether I would pass or not and get that question right does not matter. I know whoever wrote it could never enter the military due to a lack of any knowledge of the best way to structure their sentences.
Its 500 MILES
Sir has got it right
there combined speed is 30,000 miles per hour that means 30,000/60
= 500 miles
i think the wording are intensionally vague to distract.
Christina and Bear raise the two most salient points (back to back, no less), though they seem to have been ignored:
"You guys are misunderstanding the question...the question is...Did You Pass or Not?"
"Regardless of the answer, one thing is for certain, whoever wrote this question certainly didn't pass grammar school!"
The question conjugates the verb do into a past tense (did) and even conjugates the noun pass into past tense (passed?!) to boot.
Sounds like the author of the riddle is beating us over the head in order to stress that he/she is simply asking if we've already passed the test.
Of course, then, the answer to the riddle is NO.
Sir John does not indicate that we've already passed anywhere in that riddle.
You will always find some stupid people, like the above gentleman who won't try to solve anything but try to prove everyone else wrong.
May god ! give them some sense.
Amen!
grrr... I took the long way, but then it hit me.... just calculate how far each travels in a minute (missle A = 14000/60 = 233.333) (missle B = 16000/60 = 266.667), add these together and this is how far apart before they collide..... 500 miles.
After reading some other comments.... it is a math problem, (not English or grammar); if you aren't any good at math, don't try or do not comment when you are wrong. Maybe these missiles were traveling towards Earth in outer space and Earth was at the point where they collide. Have a little imagination and complete the math problem. Space is a vacuum (thus no error), so nothing would matter besides their speed and distance apart. To make this problem “more fun”, maybe add the fact that the missiles were already launched and you need to figure out the distance 1 minute before they collide to “de-activate” the destruction sequence. hehe
Note: To post here, you need to be as blunt as possible for those with little or no imagination.
It could be Eric was close to correct in the first post. If the missiles were both fired in the same direction, say east, they would be chasing each other around the globe and closing at 2000 mph. Then if you divide that by 60 to get miles per minute, you would get 33 1/3 (minus the length of the missile!) miles apart, one minute before they collide.
the answer is that we didnt pass the test cause we didnt have a paper, pencil or calculator..
they dont make it to one minute because the Commies bring them down and reuse them.
i think the answer is no cos u lot used calculators 2 wrk that out n he said he dnt have 1, so unless hes a math genius which he isnt then he failed the test.
Case Closed
the correct answer to the question is yes
the correct answer to the question is yes
Sheesh Rajesh sure is SLACKING were all waiting for the ANSWER HELLO Come ON PLEASE
hang on, guys long due Answers will be posted very soon.
hurry up all ready post the answer!!!!!!!!!!!!!!!!!!!!!!!|
Wow seriously still no authentic answer from Rajesh he is really behind what is this like three years Old!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Hurry up Rajesh Lal
Wow seriously still no authentic answer from Rajesh he is really behind what is this like three years Old!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Hurry up Rajesh Lal
Michael sorry to keep you guys waiting.
I know it is quite unfair at my end not to post answers on time
ANSWER - 500 miles
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Sir got it right
"In one minute the first missile will travel 16,000/60 and the second missile will have traveled 14,000/60 miles, so if they colide at the end of the minute they must have been
(14,000+16,000)/60 = 30,000/60 = 500 miles apart."
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RAJESH LAL
Thanks alot
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