Which of the following is the value of sin^-1(squareroot of 2/2)

These question are hard can you me with answers

Each equation given below describes a parabola. which statement best compares their graphs? x = 2y^2 x = 8y^2

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?