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Home Q & A Board Science-Related Homework Help Mathematics Statistics and Probability
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RioNii RioNii
wrote...
Posts: 268
Rep: 2 0
A year ago
Instructions:
a) Identify the type of probability distribution shown in the problem: binomial, hypergeometric, poisson etc.
b) Identify the given in the problem.
c) Solve for the probability.

4) The length of time, L hours, that a phone will work before it needs charging is normally distributed with a mean of 100 hours and standard deviation of 15 hours. Find the probability that a randomly selected phone will work greater than 127 hours before it needs charging.
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Anonymous
wrote...
#1
A year ago
This is a normal distribution model:

\(f\left(x\right)=\frac{1}{\sigma \sqrt{2\pi }}e^{-0.5\left(\frac{x-\mu }{\sigma }\right)^2}\)

Quote
The length of time, L hours, that a phone will work before it needs charging is normally distributed with a mean of 100 hours and standard deviation of 15 hours. Find the probability that a randomly selected phone will work greater than 127 hours before it needs charging.

\(\mu\) = 100
\(\sigma\) = 15
x = 127

\(z=\frac{127-100}{15}=\frac{27}{15}\)

P(x>127) = 1 - P(x≤127)

= 1 - (27/15)

Using your calculator:

normalcdf(-999,127,100,5)= 1 - .964 = .036
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