Answer: 255 meters
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Explanation:
Divide 1.5 over 2 to get 1.5/2 = 0.75
In 0.75 seconds, the sound wave goes from the person's mouth to the cave wall. Then another 0.75 seconds pass by and the echoed sound wave reaches the person's ear. So we have a total duration of 0.75+0.75 = 1.5 seconds.
Let's just focus on one leg of the trip.
The sound wave travels at a speed of 340 m/s and goes for 0.75 seconds
Meaning that,
distance = rate*time
distance = (340 m/s)*(0.75 s)
distance = (340*0.75) m
distance = 255 m
