Question 1156452
z=(x-mean)/sd=(550-500)/61=50/61=0.8 to nearest tenth

b. lasting longer than 70 days, that is z>(70/61) or z>1.15. That probability is 0.1251 or 12.51%

0.4013 is a z-score of -0.25 (invnorm)

-0.25=(x-mean)/61
-15.25=x-500
c. the value is x=484.75 or 485 days

The answers to b and c have been here since the beginning, 12.51% and 485 days