December 2014 past paper

There are 600 calls per day. 15% are for new contracts, ie 90 Of the remaining 510, 153 are terminated because customers do not know their ref number or payment number (see your earlier query) This leaves 510 - 153 who will be asked fro their password = 357. Of these 5% don't know it: 5% x 357= 17.85, rounded to 18.