A disk rotates at a rate of 7200 revolutions per minute. Seek operations (i. e., moving the access head to a desired track) take on average 20 milli-seconds. Once the access head is on the appropriate track, it takes an average of one half revolution of the disk to get to the beginning of a requested sector. Each track contains 128 sectors and each sector contains 512 bytes of data. How long on average does it take to get the access head to the beginning of a randomly selected sector on a randomly selected track? Express your answer in micro-seconds (not seconds or milli-seconds).

Write a program that keeps asking the user for new values to be added to a list until the user enters 'exit' ('exit' should not be added to the list). these values entered by the user are added to a list we call 'initial_list'. then write a function that takes this initial_list as input and returns another list with 3 copies of every value in the initial_list. finally, inside print out all of the values in the new list. for example: input: enter value to be added to list: a enter value to be added to list: b enter value to be added to list: c enter value to be added to list: exit output: a b c a b c a b c note how 'exit' is not added to the list. also, your program needs to be able to handle any variation of 'exit' such as 'exit', 'exit' etc. and treat them all as 'exit'.