5.1. The time it takes a randomly selected student to write a test is normally distributed with a mean value of t} minutes and a standard deuialion oi 1D minutes. Use the normal distribution table to calculate: [1:] MARKS] a] The probability that a randomly selected student will complete the le5t between 50 and 65 minute5? b] The probability that a randomly selected sludent will complete the task betw-Een 35 and 5t] minute5 c} The probability that a randome selected student will complete the task within 35 minute5 d] The Filriztldettilit}.r that a randomly seleuted student will eernplele the task in mere 35 minute5. 5.2. The lollowing table shows the observations at transportation times {in days} and distances {in him] [or a sample at six rail shipments made by automobile parts supplier: E---E-I- Rail distance 21:] sec 35D 431'] 490 me to destination III-In time a] Calculate the values of the intercept [a] and the gradient {b} using the least squares regression line '5.- = a + b{x]| b] Calculate the transportation time if Ihe rail distance to the customer is slim km