The following frequency table lists the sales of an item and the number of times it has occurred. It was obtained from historical records.
Sales/Frequency: 10/100, 15/120, 20/300, 25/350, 30/400, 35/500, 40/300, 45/170.
A. Make this into a probability model (round the probabilities to the nearest thousandths).
B. What is the probability of selling more than 15 units of the item?
C. What is the probability of selling between 15 and 30 untis inclusive?
D. What is the probability of selling 40 items or less? E. Are any of the events considered unusual?