Problema Solution
The average individual monthly spending in the US for paging and messaging services is $10.15. If the standard deviation is $2.45 and the amounts are normally distributed, what is the probability that a randomly selected user of these services pays more than $15.00 per month? Between $12.00 and $14.00 per month?
Answer provided by our tutors
What is the probability that a randomly selected user of these services pays more than $15.00 per month?
P(X > 15) = P(z > 1.98) = 1 - 0.9761 = 0.0239
What is the probability that a randomly selected user of these services pays between $12.00 and $14.00 per month?
P(12 < X < 14) = P(0.76 < z < 1.57) = 0.9418 – 0.7764 = 0.1654