Given a mean of 21 and a standard deviation of 1.2, what is the z-score of 21?

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?

The function show two sisters' savings account and the rate at which they plan to deposit money

The distance of a chord from the centre of a circle is 12cm and the lenght of the chord is 10cm. find the radius of the circle