Let e and f be the events that a family of n children has children of both sexes and has at most one boy, respectively. are e and f independent if a. n = 2? b. n = 4? c. n = 5?

Sound travels about 750 miles per hour. a) suppose it takes about 1.5 seconds to hear the echo. how far away is the canyon wall, in feet? for this i got 825 ft b) suppose you stand 1,925 feet from the canyon wall and sound the horn. how long will it take to hear the echo? (i'm stuck on this)