Question 1085642
Question:
a manufacturer offers a warranty on a new line of cell phones. If the average warranty offered is 48 months, with a standard deviation of 12 months, what is the probability that it will break before 24 months? Assume a normal distribution
 
We are given that the distribution is normal, with
mean=mu=48
standard deviation=sigma=12
and 
P(x<X)=Z(<(X-mu)/sigma)
therefore
P(x<24)=Z(<(24-48)/12)=Z(<-2)=0.02275 (from normal probability tables)
 
Hence
probability that the cell phone will break before 24 months is 0.02275.