Answer:
55.5 second
Explanation:
It is a problem of relative speed.
Relative speed is speed of object with respect to each other.
In relative speed
-->If two objects are moving in opposite direction with speed A and B then
there relative speed with respect to each other will be (A+B)
-->If two objects are moving in same direction with speed A and B then
there relative speed with respect to each other will be (A-B) (given speed A is quantitatively greater than speed B).
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Given
Speed of deer = 7 feet per second
Speed of beer = 3 feet per second
direction of the animals with respect to each other is opposite.
Therefore their relative speed will be ( 7 + 3 ) = 10 feet per second
This can be understood intuitively as well
if deer and beer are covering 7 feet and 3 feet in one second in opposite direction then the distance will increase between them.
distance increased between them in one second will be sum of 7 feet and 3 feet which is equal to 10 feet.
Thus, distance covered per second is nothing but speed. Here, this speed is relative to each other thus 10 feet per second is the relative of each animal
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Now in problem of speed , distance and time
Time = distance / speed
Distance = 185 yards
one yard is equal to 3 feet
so 185 yards is equal to 3*185 feet
185 yards in feet is 555 feet
Distance in feet = 555 feet
Therefore
Time = 555/10 = 55.5 second
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It will take 55.5 second until animals are 185 yards apart