Answer:
209
Step-by-step explanation:
Since the lead time is 2 periods at the time of order, the stocks should last for 3 periods with the 90% probability.
The z-value of 90$ in stock probability = 1.7
Mean of the demand over is (1 + 1 + 1 ) or (2+1 which is 3)
= 60 x 3 = 180
Now the standard deviation of demand over the three periods = 17.3
Therefore, the order up level would be = 180 + ( 1.7 x 17.3 )
= 209