A bat emits ultrasonic pulses and uses them to navigate and to locate flying insects. If these pulses are sent

A bat emits ultrasonic pulses and uses them to navigate and to locate flying insects. If these pulses are sent at a rate of 2 per second, what is the maximum distance a reflecting object can be if the reflected pulse is to be received by the bat before the next pulse is emitted? (The speed of sound in air is 344 m/s.)

So, since the bat sends out 2 pulses per second, the first pulse has to go out and back in half a second. So that's 1/4 sec out and a 1/4 of a sec to get back. In 1/4 of a second, the sound wave can travel
344/ 4 = 86 m
so this is the max range from the bat.