I need help with part c of this question. Please show me step by step how to answer.

Avoiding an accident while driving can depend on reaction time. That time, measured from the moment the driver first sees danger until they step on the brake pedal, follows an approximately normal distribution with a mean time of 1.5 seconds and a standard deviation of 0.18 of a second.

A. What percent of drivers have a reaction time less than 1.25 seconds?

P(x<1.25)= P(z<1.25-1.5/ 0.18)= P(z<-0.25/0.18)= P(z<-1.3888)= P(z<-1.39)= 0.0823= 8.23% (Calculated in Geogebra)

8.23% of drivers have a reaction time less than 1.25 seconds.

B. What percent of drivers have reaction times between 1.6 and 1.8 seconds?

P(1.6

24.13% of drivers have a reaction time between 1.6 and 1.8 seconds.

C. What's the cut-off for the reaction times of the slowest 1/3 of all drivers, those drivers with the longest 1/3 of the reaction times?