Permutation Combination Question 19
Question 19 - 01 February - Shift 2
Number of integral solutions to the equation $x+y+z=21$, where $x \geq 1, y \geq 3, z \geq 4$, is equal to ________
Show Answer
Answer: 105
Solution:
Formula: Selection Formula
${}^{15} C_2 = \frac{15 \times 14}{2} = 105$