Agroup of nine singers includes 6 altos and 3 sopranos. an instructor randomly selects one of the singers to sing the first part of a duet and a different singer to sing the second part of a duet. use a sample space to determine whether randomly selecting an alto first and randomly selecting a soprano second are independent events.

show us the triangle so we can answer it

in counting the number of heads in 4 coin flips, the probability that we get exactly one head is the probability that we get anyone of the following 4 outcomes: httt, thtt, ttht, or ttth. each has probability 1/16, so the probability to get exactly one head in 4 flips is 1/16 + 1/16 + 1/16 + 1/16 = 4/16 = 1/4.