The time that it takes to react to the brake lights on a decelerating vehicle is critical in avoiding rear-end collisions. Research suggests that reaction time for an in-traffic response to a brake signal from standard brake lights can be modelled with a normal distribution having a mean of 1.24 seconds and a standard deviation of 0.45 seconds.
a) Identify the variable of interest and the unit of measurement
b) What proportion of reaction times are less than 2.00 seconds?
c) What percentage of reaction times are between 1.00 seconds and 1.75 seconds?
d) Below what reaction time are the fastest 20% of these in-traffic responses?