Question:
What is the number of selections of at most 3 things from 6 different things?
What is the number of selections of at most 3 things from 6 different things?
Options:
- a) 20
- b) 22
- c) 41
- d) 42
- a) 20
- b) 22
- c) 41
- d) 42
correct answer : d)
Explanation:
Number of selections (at most 3
things)
= 6C0 + 6C1 + 6C2 + 6C3
= 1 + 6 + 65
21
·
·
+
65 4
32 1
··
··
= 1 + 6 + 15 + 20 = 42
NDA / NA
National Defence Academy /
Naval Academy
SOLVED PAPER
2025
MATHEMATICS
I
ANSWERS WITH EXPLANATIONS
Solved Paper – 2025 (I)
Number of selections (at most 3
things)
= 6C0 + 6C1 + 6C2 + 6C3
= 1 + 6 + 65
21
·
·
+
65 4
32 1
··
··
= 1 + 6 + 15 + 20 = 42
NDA / NA
National Defence Academy /
Naval Academy
SOLVED PAPER
2025
MATHEMATICS
I
ANSWERS WITH EXPLANATIONS
Solved Paper – 2025 (I)