The amount of time to complete a physical activity in a PE class is approximately normally normally distributed with a mean of 38.2 seconds and a standard deviation of 6.7 seconds.

Question

a) What is the probability that a randomly chosen student completes the activity in less than 31.9 seconds? 

b) What is the probability that a randomly chosen student completes the activity in more than 43.4 seconds? 

c) What proportion of students take between 34.3 and 41.6 seconds to complete the activity? 

d) 85% of all students finish the activity in less than  seconds.

Answer 1

a) What is the probability that a randomly chosen student completes the activity in less than 31.9 seconds? 0.1735

b) What is the probability that a randomly chosen student completes the activity in more than 43.4 seconds? 0.2188

c) What proportion of students take between 34.3 and 41.6 seconds to complete the activity? 0.4138

d) 85% of all students finish the activity in less than  seconds. 45.14