QCEVault

Continuous random variables and the normal distribution — Question 307

Original QCE Vault practice · 4 marks

Q307 · Practice questionTechnology-activeSimple familiar4 marks

QUESTION 307 (4 marks)

Battery life XX hours is normally distributed with mean 4848 hours and standard deviation 66 hours.
Normal density with mean 48 and standard deviation 6; the interval 42<x<55 is hatched.
a)
Determine P(42<X<55)P(42<X<55), to four decimal places.
[2 marks]
b)
Determine the battery life exceeded by only 10%10\% of batteries, to 0.10.1 hour.
[2 marks]
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