3. A local manufacturer creates distress flares. The times the flares last are normally distributed with a mean life of 9.8 years and a standard deviation of 1.3 years.(adsbygoogle = window.adsbygoogle || []).push({});

(b) A small boat owner who regularly travels out to sea wants to be sure his distress flare works. Determine when he should replace the distress flare, given he wants a better than:

(i) 90% chance the flare will work

(ii) 99% chance the flare will work.

For this question i am not sure what to do.. I thought that if it had said works for.. 11years you'd do z = (11-9.8)/1.3 then use this value to find out the proability. but with the percentages i am unsure. Could some please help me! much apprechiated.! :_)

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# Homework Help: Normal distribution

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