Answer: a. 20 and b.10
Step-by-step explanation:
Given Letters = A, B, C, D, and E
Number of letters given = 5
a. When we choose 2 letters, without replacement from the 5 letters and order of the choices is relevant we use permutations.
Then, the number of ways we can choose 2 letters from 5 =
[∵
]
So , when order of the choices is relevant , the total number of way to do this = 20
b. When we choose 2 letters, without replacement from the 5 letters and order of the choices is not relevant we use combinations.
Then, the number of ways we can choose 2 letters from 5 =
[∵
]
So , when order of the choices is not relevant , the total number of way to do this = 10