Respuesta :
Answer:
They should warranty the product for 7 years if they want no more than 6.7% of the waffle irons to fail within that time.
Step-by-step explanation:
Normal Probability Distribution:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the z-score of a measure X is given by:
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.
The average waffle iron lasts for 12 years and one standard deviation is 8 months.
Measuring the time in months, we have that [tex]\mu = 12*8 = 96[/tex] and [tex]\sigma = 8[/tex]
How long should they warranty the product for if they want no more than 6.7% of the waffle irons to fail within that time?
This is X when Z has a p-value of 0.067, so X when Z = -1.5. Then
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]-1.5 = \frac{X - 96}{8}[/tex]
[tex]X - 96 = -1.5*8[/tex]
[tex]X = 84[/tex]
84 months = 7 years.
They should warranty the product for 7 years if they want no more than 6.7% of the waffle irons to fail within that time.
