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.)

 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%. 

you had the wrong answer