Surveys conducted in american high schools concluded that 90% of the students in a sample of 400 students had more than one active email
account. what would the margin of error be for the population proportion?

Ijust need to see how to do this. so you don’t have to answer all of them just a step by step explanation of one.

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?

Jayne is studying urban planning and finds that her town is decreasing in population by 3% each year. the population of her town is changing by a constant rate.true or false?