NOWWWW URGENT!!!

1-the time needed to complete a final examination in normallyu a particular college course is distributed with a mean of 70 minutes and a population standard deviation of 15 minutes.

how long does it take for the fastest and the smartest 10% if students to complete the exam?

2- Do you dislike waiting in the line ? Supermarket chain kroger has used computer simulation and information technology to reduce the average waiting time for customers at 2300 stores. Using a new system called new-vision. Which allows kroger to better predict when shoppers will be checkig out, the company was able to decrease average customer waiting time to just 35 seconds(information week website).

Calculate the standard deviation of time for the waiting time?