A student is picked at random from a class containing 17 boys and 13 girls. what is the probability that the students is a girl.​

2people are trying different phones to see which one has the better talk time. chatlong has an average of 18 hours with a standard deviation of 2 hours and talk-a-lot has an average of 20 hours with a standard deviation of 3. the two people who tested their phones both got 20 hours of use on their phones. for the z-scores i got 1 for the chatlong company and 0 for talk-a-lot. what is the percentile for each z-score?

3.4a=57.8 what is the the value of a

Using only the digits 5, 6, 7, 8, how many different three digit numbers can be formed if no digit is repeated in a number?