Ten discs with a different number (0, 1, 2 . . .. 9) printed on them are placed in a bag.

Two discs are taken out of the bag one at a time at random to form a two digit number (where 08 is counted as the number 8). Assuming the first disc is replaced before the second is chosen, fi nd the following probability that: 

(a) The number is even; 

(b) The number is less than 30; 

(c) The number is 67; 

(d) The two digits forming the number are equal. 

What would happen to your answers to (a)–(d) if the first disc is not replaced before the second is chosen?