Two different numbers taken from 0,1,,10.

Question

Two different numbers taken from $\{0,1,\dots,10\}$. Find the probability their sum and absolute difference are both multiples of 4.

Accepted Answer

$n(S)={}^{11}C_2=55$. Favourable: $(0,4),(0,8),(2,6),(2,10),(4,8),(6,10)$ --- 6 pairs.

$$P = \frac{6}{55}$$

Solutions · 1