SOLUTION: The probability that an appliance is in repair is 0.5. If an apartment complex has 100 such appliances, what is the probability that at least 60 will be in repair? Use the normal

Algebra ->  Probability-and-statistics -> SOLUTION: The probability that an appliance is in repair is 0.5. If an apartment complex has 100 such appliances, what is the probability that at least 60 will be in repair? Use the normal      Log On


   

Question 721016: The probability that an appliance is in repair is 0.5. If an apartment complex has 100 such appliances, what is the probability that at least 60 will be in repair? Use the normal approximation to the binomial.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
The probability that an appliance is in repair is 0.5. If an apartment complex has 100 such appliances, what is the probability that at least 60 will be in repair? Use the normal approximation to the binomial.
------
mean = np = 100*0.5 = 50
std = sqrt(npq) = sqrt(50*0.5) = 5
------
P(59.5<= x <= 100.5) = ?
-------
z(59.5) = (59.5-50)/5 = -0.1
----
z(100.5) = (100.5-50)/5 = 50.5/5 = 10.1
----------
= P(-0.1<= z <=10.1) = 0.5398
=====================================
Cheers,
Stan H.
=================