QCEVault

Continuous random variables and the normal distribution — Question 374

Original QCE Vault practice · 5 marks

Q374 · Practice questionTechnology-activeComplex unfamiliar5 marks

QUESTION 374 (5 marks)

An outlet sells two types of rechargeable battery. Type A accounts for 70%70\% of batteries sold and has operating time N(8,12)N(8,1^2) hours. Type B accounts for 30%30\% and has operating time N(10,22)N(10,2^2) hours. A randomly selected battery operates for more than 1010 hours.
a)
Determine the probability that a randomly selected battery operates for more than 1010 hours, to four decimal places.
[3 marks]
b)
Determine the probability that the observed battery is type B, to four decimal places.
[2 marks]
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