Respuesta :
Answer:
0.04% probability that a laser fails before 5000 hours
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the zscore 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 pvalue, we get the probability that the value of the measure is greater than X.
In this problem, we have that:
[tex]\mu = 7000, \sigma = 600[/tex]
What is the probability that a laser fails before 5000 hours
This is the pvalue of Z when X = 5000. So
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]Z = \frac{5000 - 7000}{600}[/tex]
[tex]Z = -3.33[/tex]
[tex]Z = -3.33[/tex] has a pvalue of 0.0004.
0.04% probability that a laser fails before 5000 hours
