PLEASR HELP ME, WILL GIVE BRAINLIEST a sportsman rushed the circle 15 times in 1/6 hour. distance of this running track 0.4 km. what is the average speed of sportsman?

a) 20 m/s
b) 50 m/s
c) 35 m/s
d) 10 m/s
e) 25 m/s
f) 20.5 m/s

(an answer with explanation would be great)

Two loudspeakers, 5.5 m apart and facing each other, play identical sounds of the same frequency. you stand halfway between them, where there is a maximum of sound intensity. moving from this point toward one of the speakers, you encounter a minimum of sound intensity when you have moved 0.33 m . assume the speed of sound is 340 m/s. part a) what is the frequency of the sound? part b) if the frequency is then increased while you remain 0.21 m from the center, what is the first frequency for which that location will be a maximum of sound intensity? express your answer to two significant figures and include the appropriate units.