a) The time taken for field workers to mark out a plot for logging is normally distributed with a mean of 75 minutes and a standard deviation of 15 minutes. What is the probability that the time is between 70 and 90 minutes? (You need to use an appropriate Excel function to determine the probability.)

b) A logger knows that, on average, it takes two hours to clear eleven tree roots. Find the probability that a logger will clear at most five tree roots in a one hour period.

c) If the probability of finding a tree species with an extensive subterranean root system is 0.43 and five plots were selected, find the probability that at most two of the six plots contain a tree species with an extensive subterranean root system.

d) Can we conclude at the 10% significance level that logging significantly reduces the number of species in a plot after a decade? Here we want you to highlight the relevant critical value or p-value and the test statistic to aid you in interpreting the data.

I know these may seem basic to some but I'm only just starting to dip my feet in this (as I am an intern who is asked to learn) and would really appreciate some help or guidance on how to go about doing this. Thank you so much in advance!