Answer:
True
Step-by-step explanation:
Data
mean ([tex]\mu[/tex]) = 516 hours
standard deviation ([tex]\sigma[/tex]) = 20 hours
expected lifetime (X) = 541.6 hours
In the figure attached, standard normal distribution table can be seen. Z is computed as follows:
[tex]Z = \frac{X - \mu}{\sigma}[/tex]
[tex]Z = \frac{541.6 - 516}{20}[/tex]
[tex]Z = 1.28[/tex]
In table can be seen that the area between 0 and 1.28 is 0.3997, or simply 0.4. The area until Z = 0 is 0.5; so, the total area until Z = 1.28 is 0.9. That means 90% of batteries would have 541.6 lifetime hours.
