Two cars started simultaneously towards each other at constant rates of 20 miles per hour and 30 miles per hour, respectively. How much time is required for these cars to cross each other, if initially they are separated by a distance of 1320 yards? (1 mile = 1760 yards)
[A] 54 sec.
51 sec.
[C] 52 sec.
[D] 53 sec.
[E] 44 sec
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theCEO
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1320 yards = 0.75miles
speed x time = distance
both cars travel a total distance of 0.75miles
speed of car 1 x time + speed of car 2 x time = total distance cars travellled
20miles/hr x a + 30miles/hr x a = 0.75miles
a(20miles / hr + 30miles/hr) = 0.75miles
a(50miles/hr) = 0.75miles
a = 0.75miles/(50miles/hr) = 0.015hr
0.015hr = 0.015*60*60 = 54sec
ans = a
speed x time = distance
both cars travel a total distance of 0.75miles
speed of car 1 x time + speed of car 2 x time = total distance cars travellled
20miles/hr x a + 30miles/hr x a = 0.75miles
a(20miles / hr + 30miles/hr) = 0.75miles
a(50miles/hr) = 0.75miles
a = 0.75miles/(50miles/hr) = 0.015hr
0.015hr = 0.015*60*60 = 54sec
ans = a
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\'manpreet singh
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AJWILL wrote:Two cars started simultaneously towards each other at constant rates of 20 miles per hour and 30 miles per hour, respectively. How much time is required for these cars to cross each other, if initially they are separated by a distance of 1320 yards? (1 mile = 1760 yards)
[A] 54 sec.
51 sec.
[C] 52 sec.
[D] 53 sec.
[E] 44 sec
This kind of question can be solved by relative speed concept easily:
Since the cars are moving towards each other, we can add up their speeds= 30 + 20=50 miles/hr
Now the distance is 1320 yards, convert it in miles= 1320/1760=.75 miles
time(T) = distance/speed= .75/50 hr
T = .75/50 * 3600 sec
T= 54 sec
Hope it clears the doubt
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Cosmas
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Let the two cars be A and B.
Car A travels at 20miles/hour
Car B travels at 30miles/hour
The distance between the cars is reducing at a rate of 50miles/hour(THE KISS:MGMAT WORD TRANSLATIONS)
Covert 50miles/hour to miles/second=1/72 miles per second.
Convert 1320 yards into miles=3/4miles.
So to get the time in seconds:
3/4miles(total distance) divided by 1/72 miles per second=54seconds.
So answer is A
Car A travels at 20miles/hour
Car B travels at 30miles/hour
The distance between the cars is reducing at a rate of 50miles/hour(THE KISS:MGMAT WORD TRANSLATIONS)
Covert 50miles/hour to miles/second=1/72 miles per second.
Convert 1320 yards into miles=3/4miles.
So to get the time in seconds:
3/4miles(total distance) divided by 1/72 miles per second=54seconds.
So answer is A
