× logo

The Free 30-Day CAT RC Course

"It is designed to help you excel in the upcoming CAT 2024 exam"

-By Lavleen Kaur Kapoor. Over 2,00,000+ Subscribers

read more

No thanks >

Question

Sum of three Natural numbers a, b and c is 10. How many ordered triplets (a, b, c) exist

A
45
CORRECT ANSWER WRONG ANSWER
B
36
CORRECT ANSWER WRONG ANSWER
C
54
CORRECT ANSWER WRONG ANSWER
D
28
CORRECT ANSWER WRONG ANSWER
Solution

Correct option is

(B)

Explanatory Answer

a + b + c = 10 , Let us place 10 sticks in a row

| | | | | | | | | |

now place two " + "

| | | | + | | | | | + |

This will become 4 + 5 + 1 , OR , a = 4 , b = 5 , c = 1

hence we hace 9 slots out of which 2 has to be selected for " + " s

now , number of ways = = 36

hence B is the correct option