The lifespan of a certain electronic toy is normally distributed, with a mean of 3000 hours and a standard deviation of 35 hours. Use a standard normal distribution table
or a graphing calculator to find the proportion of toys that have a lifespan between
2920 hours and 2945 hours.

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?

What are the solutions of the system? solve by graphing. y = -x^2 -6x - 7 y = 2

Apool measures 12.3 feet by 16.6 feet. if the longer wall of the pool has a diagonal of 17.8 feet, what is the volume of the pool? (round to nearest tenth)