The finance department of a large organisation has responsibility for monitoring costs in other departments of the organisation. A photocopier facility is available for one department’s use and data has been collected which reveals that the number of photocopies made on the machine on a daily basis follows the Normal distribution; the mean of the distribution is 380 copies per day with a standard deviation of 35.

The cost per copy is estimated at 6p.

(a) Determine the probability that daily costs incurred on the photocopier machine will be:

● more than £25;

● less than £22.50;

● between £24 and £26.

(b) Explain the basis of your calculations in a short memo to the finance director.