Paulo got these markers in three tests: 72, 80 and 82. He had one more test to sit. He wanted an average of 80 for the four tests. What mark must he get in the fourth test?
78
80
86

Suppose you just purchased a digital music player and have put 8 tracks on it. after listening to them you decide that you like 4 of the songs. with the random feature on your player, each of the 8 songs is played once in random order. find the probability that among the first two songs played (a) you like both of them. would this be unusual? (b) you like neither of them. (c) you like exactly one of them. (d) redo () if a song can be replayed before all 8 songs are played.