I don't want the answer but an explanation on how to answer this problem.
A car is designed to last an average of 12 years with a standard deviation of 0.8 years. What is the probability that a car will last less than 10 years?

Question

I don't want the answer but an explanation on how to answer this problem.
A car is designed to last an average of 12 years with a standard deviation of 0.8 years. What is the probability that a car will last less than 10 years?

faiqraees · Answer

Are we supposed to use the normal distribution curve here?

phi · Answer

You can "sketch a bell curve"  centered at 12, with a "standard width" of 0.8 years
(it helps to think *roughly* all of the area of the bell is between -3 and 3 "widths")
in this case, between -3*0.8  and +3* 0.8  or  -2.4 years (below 12) and 2.4 years (above 12)
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