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If an object travels 100 feet in 2 seconds, what is the [#permalink]
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21 Oct 2010, 18:42
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If an object travels 100 feet in 2 seconds, what is the object’s approximate speed in miles per hour? (Note: 1 mile = 5280 feet) A. 3.4 B. 3.8 C. 34 D. 38 E. 340
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Re: conversion [#permalink]
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21 Oct 2010, 19:01
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Re: conversion [#permalink]
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22 Oct 2010, 05:02
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Conversion questions are best dealt using a one step approach. Let me illustrate: Let's say we want to convert a speed of 100 miles/hour to feet/sec. Speed = 100 miles/1 hour = (100 x 5280 feet)/(1 x 3600 sec)= 146.67 feet/sec So, simply convert the units to what you want along with the conversion factor. Let's take your question now. If an object travels 100 feet in 2 seconds, what is the object’s approximate speed in miles per hour? (Note: 1 mile = 5280 feet) Speed = 100 feet/2 sec = (100×1/5280 miles)/(2×1/3600 hour) = 5x3600 miles/528 hr = 34 miles/hr Note: Since 1 mile = 5280 feet, hence here to convert we say 1 foot = 1/5280 miles.
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Re: conversion [#permalink]
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22 Oct 2010, 05:55
Bunuel wrote: shrive555 wrote: If an object travels 100 feet in 2 seconds, what is the object’s approximate speed in miles per hour? (Note: 1 mile = 5280 feet) 3.4 3.8 34 38 340 i always mess such conversion questions. \(100\) feet in 2 seconds; \(100*\frac{3,600}{2}=50*3,600\) feet in 1 hour; \(\frac{50*3,600}{5,280}\approx{34}\) miles in 1 hour. Answer: C. thanks for your better explanation......



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Re: If an object travels 100 feet in 2 seconds, what is the object's appro [#permalink]
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13 May 2011, 08:46
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1 mile = 5280 feet => 1 feet = 1/5280 miles If the object ravels 100 feet in 2 sec then it travels 100/2 * 60 * 60 feet in 1 hour (1 hr = 60 min * 60 sec) = 3600 * 50 feet in 1 hour = 180000 feet in 1 hr = 180000/5280 miles in 1 hour = 18000/528 miles/hr ~ 34 miles/hr Answer  C
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Re: If an object travels 100 feet in 2 seconds, what is the object's appro [#permalink]
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13 May 2011, 08:49
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In 2 seconds 100feet In 1 second50feet In 3600 seconds(1hour=3600sec)3600*5feet. Now 5280 feet = 1 miles so, 3600*5 feet= 3600*5/5280. Now use approximation.. (36*5)/5280 * 100 = 180/5280 *100 or 18/5280 * 1000= 3/88 *1000. Now 3/90= 1/30= .03 So 3/88*1000 ~ .03*1000=33.3~34. Idea is to not multiply anything until last few steps when you can use approximation better.
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Re: If an object travels 100 feet in 2 seconds, what is the object's appro [#permalink]
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13 May 2011, 11:32
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speed= 100 feet/2 sec = 50 feet /1 sec = 50*60*60 feet / hours Now divide the entire distance traveled into number of miles it gives 18000/5280 ~35 Hence choice c
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Re: conversion [#permalink]
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08 Jul 2012, 10:50
100 (feet)/2 (sec) *1 (mile)/5280 (feet)* 3600 (sec)/1 (hour) > cancel out (feet) and (sec) and you will get
(100*3600)/(2*5280) = 34.09



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Re: If an object travels 100 feet in 2 seconds, what is the [#permalink]
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19 Jul 2012, 04:25
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1 mile = 5280 feet => 1 feet = 1/5280 mile 1 hr = 3600s => 1s = 1/3600 hr If an object travels 100 feet in 2 seconds => speed = 100/2 feet/s = 50 feet/s = 50 *(1/5280) / (1 *(1/3600)) miles/hr = 3600 * 50 / (5280) miles/hr = 18000/ 528 miles/hr ~ 18000/525 = 180 * 4/ 21 miles/hr = 240/7 miles/hr ~ 34miles/hr So, Answer is C(34) Hope it helps!
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Re: conversion [#permalink]
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17 Oct 2013, 04:37
Bunuel wrote: shrive555 wrote: If an object travels 100 feet in 2 seconds, what is the object’s approximate speed in miles per hour? (Note: 1 mile = 5280 feet) 3.4 3.8 34 38 340 i always mess such conversion questions. \(100\) feet in 2 seconds; \(100*\frac{3,600}{2}=50*3,600\) feet in 1 hour; \(\frac{50*3,600}{5,280}\approx{34}\) miles in 1 hour. Answer: C. Thanks! nice explanation! helped me understand.



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Re: conversion [#permalink]
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17 Oct 2013, 04:42



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Re: If an object travels 100 feet in 2 seconds, what is the [#permalink]
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20 Sep 2014, 09:05
shrive555 wrote: If an object travels 100 feet in 2 seconds, what is the object’s approximate speed in miles per hour? (Note: 1 mile = 5280 feet)
A. 3.4 B. 3.8 C. 34 D. 38 E. 340 My approach is as follows: 100 feet in 2 Secs. Therefore 50 feet in 1 Sec 50 X 60 =3000 Feet in 1 Min And 3000 X 60 = 180000 Feet in 1 Hour Now Conversion..... 180000/5280~=180000/5000=36 The answer should be slightly less than 36.That is C.



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Re: If an object travels 100 feet in 2 seconds, what is the [#permalink]
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26 Jul 2015, 16:53
Bunuel wrote: shrive555 wrote: If an object travels 100 feet in 2 seconds, what is the object’s approximate speed in miles per hour? (Note: 1 mile = 5280 feet)
\(\frac{50*3,600}{5,280}\approx{34}\) miles in 1 hour. Answer: C. How do you do that math fast and not screw it up? That's what I screwed up on this problem.



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Re: If an object travels 100 feet in 2 seconds, what is the [#permalink]
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26 Jul 2015, 16:58
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gmatser1 wrote: Bunuel wrote: shrive555 wrote: If an object travels 100 feet in 2 seconds, what is the object’s approximate speed in miles per hour? (Note: 1 mile = 5280 feet)
\(\frac{50*3,600}{5,280}\approx{34}\) miles in 1 hour. Answer: C. How do you do that math fast and not screw it up? That's what I screwed up on this problem. You can use approximation as the given options are spread far and wide Lets take the example of this question: \(\frac{50*3,600}{5,280}\) Recognize here that 36 = 18*2 and 54 = 18*3. 5280 is almost equal to 5400. Thus you can cancel out 3600 and 5280 to get 2/3 (approx.). For approximations of fractions, you need to a bit imaginative to cancel out the maximum you can. Now the given equation reduces to 50*2/3 = 100/3 = 33.33333 which is very close to 34. Hope this helps.



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Re: If an object travels 100 feet in 2 seconds, what is the [#permalink]
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03 Apr 2016, 10:34
shrive555 wrote: If an object travels 100 feet in 2 seconds, what is the object’s approximate speed in miles per hour? (Note: 1 mile = 5280 feet)
A. 3.4 B. 3.8 C. 34 D. 38 E. 340 my approach 100ft/2sec = 50ft/sec or 3000ft/min, or 180,000/hour now..1 mile is 5280 180,000/5000 = 36 so clearly is less than 36, but smth around 30 only option C



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Re: If an object travels 100 feet in 2 seconds, what is the [#permalink]
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19 Nov 2016, 17:31
difficult question. I get to the below with some work
50 *3,600/ 5,280
then I decided to approximate = 18,000/5,000 = 36.
at this point I had to decide between 34 and 38. That was the difficult part of me.



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Re: If an object travels 100 feet in 2 seconds, what is the [#permalink]
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09 Feb 2018, 22:45
100 feet per 2 seconds , which translates to 3000 ft per minute. Speed for 1 hour = (3000 * 60) / 5280 = ~ 34 Ans: C
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Re: If an object travels 100 feet in 2 seconds, what is the [#permalink]
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19 Apr 2018, 04:52
1) First change 100ft/2seconds to 50ft/1second. 2) Convert feet to miles = 50 * 1 / 5280 = 50/5280 3) Convert seconds to hours = 1 / (60)^2 = 4) Divide – multiply reciprocal = (60)^2*50/5280. 5) 3600*50=180000/5280. 6) By looking at this fraction we conclude that it needs to be multiplied by at least 30. Thus therefore 34. Multiplying times 8 would be make the number too large
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