Answer: 22 units
Explanation:
Given
lead time = 7
mean = 15
Standard Deviation = 5
service level = 95%
Using the formulae
Safety stock = safety factor ( z value) x standard deviation x [tex]\sqrt{lead time}[/tex]
But
Z value for 95% service level = 1.645 = safety factor
= 1.645 x 5 x [tex]\sqrt{7}[/tex]
=21.76 which estimates to 22units