Question

If accrotime guarantees a full refund on any defective watch for 2 years after purchase, what percentage of total production will the company expect to replace? (round your answer to two decimal places.)

Answer 1

21.19%

Step-by-step explanation:

to find this on a calculator press 2ND and then VARS to get to the distribution list. Press the second option which is normalcdf(.
Enter the lower limit as negative infinity, because you want everything less than 24 months. To do this, enter -1e99 [(-),1, 2nd and then hit the comma button and EE will appear, 99]
for the upper limit we want to use 24 for the 24 month cutoff. The mean is 28, and the standard deviation is 5. It will paste like this normalcdf(-1e99,24,28,5) hit enter and the answer .2118553337 will pop up. This means the answer is 21.19% after rounding

Answer 2

The problem is missing some parts but nevertheless here is the solution:

Given:

Mean is 28

Standard deviation is 5

So we denote the problem as x <= 2

For X ~ N (28, 5^2)
we are looking for the percentage:

P{X>24} = P {Z>z}

Where z = (24-28)/5 = 4/5 = - 0.80.

P {Z> -0.80} = 1 - P{Z< -0.80} = 1 - 0.2119.

Or in percentage, it is replaced as P{Z< -0.80} = 0.2119, 21.19%.