9709 P53 - Nov 2021 - Q5 - 8 marks
2812
A security code consists of 2 letters followed by a 4-digit number. The letters are chosen from {A, B, C, D, E} and the digits are chosen from {1, 2, 3, 4, 5, 6, 7}. No letter or digit may appear more than once. An example of a code is BE3216.
(a) How many different codes can be formed? [2]
(b) Find the number of different codes that include the letter A or the digit 5 or both. [3]
A security code is formed at random.
(c) Find the probability that the code is DE followed by a number between 4500 and 5000. [3]
