You are at The Mall of America searching for a new cell phone. You have identified two plans that work for you. The First Plan is
through Fast Communications. The Second Plan is through
Alltell Wireless. Fast Communications charges a monthly fee of
|$15.20 for text messaging, call waiting and caller ID. Fast Communications also charges you 7 cents per minute to use the
phone. Alltell Wireless charges a monthly fee of $9.50 for text
messaging, call waiting and caller ID. Alltell Wireless also charges you 9 cents a minute to use the phone. How many minutes
per month do you need to use a phone for the two plans to cost
the same?

step-by-step explanation:

what grade level is this? need to know so i can look in my old textbooks!

x equals 1

step-by-step explanation:

f(4)=f(×)

x=1

no its the same as every other grade

step-by-step explanation:

irst, find the z score of a score of 80. this is given by the formula z = (x-u)/o, where x is the score, u is the mean, and o is the standard deviation. this gives

z = (80-78)/12 = 1/6 = .1667

now, find what percentile a z score of 1/6 correlates to in the normal distribution.

a z score of 1/6 = .1667 is equivalent to the 56.36th percentile of the distribution. so the probability a score is over this is 1-.5636 = .4364

the mean of a sample mean is equal to the original mean. however, the standard deviation of a sample mean is equal to the original standard deviation divided by the square root of n (sample size). so the new standard deviation is 12/sqrt(16) = 3.

the new z score is 80-78/3 = 2/3 = .667. this is equivalent to the 74.86th percentile. so the probability that the mean will be greater than this score is 1-.7486 = .2514.