Answer:
11414.87205 units.
Step-by-step explanation:
We have Underage cost cs to be $500
We have Overage cost Co to be $200
To get Critical fractile, we do this computation:
Cs/(Cs+Co)
500/(500+200)
500/700
0.714285714
Now the z score for this value,
normsinv(0.714285714)
= 0.565948821
To get what the question requires: mean+z-score*standard deviation
= 10000+(0.565948821*2500)
= 11414.87205 units
please note: I solved this without rounding the values.
We will have 10000+(0.57*2500)=11425 units if rounded