Assume the mean useful life of a particular light bulb is 2,000 hours and is normally distributed with a standard deviation of 3
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Answer:
18 years
Step-by-step explanation:
The formula for computing accrued amount A for a principal of P at an interest rate of r(in decimal) compounded n times in a year for t years is given by
Note that r is percentage converted to decimal. So 3% = 3/100 = 0.03
We can rearrange the above equation to:
Taking logs on both sides
This gives
In this particular problem, n = 4, , A= 9600, P = 5600, r =0.03, so r/n = 0.03/4 = 0.0075
1 + r/n = 1+0.0075 = 1.0075
4t = log(9600/5600)/log(1.0075) = log(1.714) / log(1.0075) = 0.234 /0.00325 = 72
t = 72/4 = 18 years