SOLUTION: A phone company has determined that the length of its customers' calls is normally with a mean of 2.87 minutes and a standard deviation of 1.51 minutes.
Find the probability th
Algebra.Com
Question 364862: A phone company has determined that the length of its customers' calls is normally with a mean of 2.87 minutes and a standard deviation of 1.51 minutes.
Find the probability that a customers' call will last for more than 4 minutes.
the probability that a customer's call will last between 1.1 and 3.2 minutes.
the 21st percentile for the length of telephone calls (a time such that 21% of calls are less than that time)
the probability that a random sample of 30 calls has a mean length of more than 3.43minutes
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
A phone company has determined that the length of its customers' calls is normally with a mean of 2.87 minutes and a standard deviation of 1.51 minutes.
-----------------------
Find the probability that a customers' call will last for more than 4 minutes.
z(4) = (4-2.87)/1.51 = 0.7483
P(x > 4) = P(z > 0.7483) = 0.2271
===============================================
the probability that a customer's call will last between 1.1 and 3.2 minutes.
Find the z-values of 1.1 and 3.2
Find the area under the normal curve over that z interval.
I get: 0.4659
===============================================
the 21st percentile for the length of telephone calls (a time such that 21% of calls are less than that time)
invNorm(0.21) = -0.8064
x = -0.8064*1.51+2.87 = 1.6523
===============================================
the probability that a random sample of 30 calls has a mean length of more than 3.43minutes
t(3.43) = (3.43-2.87)/[1.51/sqrt(30)] = 2.0313
----
P(x-bar < 3.43) = P(t> 2.0313 when df=29) = 0.0257
==================================================
Cheers,
Stan H.
RELATED QUESTIONS
A major cell phone service provider has determined that the number of minutes that its... (answered by stanbon)
1. A supermarket manager has determined that the amount of time customers spend in the... (answered by tommyt3rd)
10.48 From her firm’s computer telephone log, an executive found that the mean length of... (answered by stanbon)
A recent study of long distance phone calls made from WPU, showed that the length of the... (answered by stanbon)
A local bank has determined that the daily balances of the checking accounts of its... (answered by Boreal)
Please help me Thank you in advance
A major credit card company has determined that the... (answered by Theo)
Length of cell phone calls is exponetially distributed with a mean of 2 minutes.
Find... (answered by ewatrrr)
The duration of phone calls to a Calling Centre is normally distributed with a mean of... (answered by ewatrrr)
Customers of a phone company can choose between two service plans for long distance... (answered by jim_thompson5910)