(b) The table below indicates the cost of certain air tel kiosk Z 0.15 0.20 0.25 0.75 0.80 0.85 1.85 1.90 1.95 2.00 2.05 QZ 0.0596 0.0793 0.0987 0.2734 0.2881 0.3023 0.4678 0.4713 0.4744 0.4772 0.4798 If it was stated that the number of telephone calls received at a switchboard is approximately normal with a mean of 580 calls and a standard deviation of 10. REQUIRED ind the possibility that on a given day the number of calls received at the switchboard will be; (a) Exactly 578 (6) Less than 57 (c) Between 561 and 600 inclusive