Answer:
a) 24
b) 12
Step-by-step explanation:
a) For the 4 letters of the word ROCK
Selecting any first letter, we have 4 options
for the second, we have 3 options
for the third we have 2 options
for the fourth, we have only one option
So the number of ways will be ;
4 * 3 * 2 * 1 = 24 ways
b) 2 out of 4
For the first letter, we have 4 options, for the second, we have 3 options
so the number of options is 4 * 3 = 12 options