Answer
$\displaystyle \frac{41}{42}$
Work Step by Step
$P(E)=\displaystyle \frac{\text{Number of favorable outcomes}}{\text{Total number of outcomes}}=\frac{n(E)}{n(S)}$
$n(S)=C(10,5)=252$
$E$ = not all red.
In exercise 1, we found P(all red)=$\displaystyle \frac{1}{42}$
S0, $P(E)=1-\displaystyle \frac{1}{42}=\frac{41}{42}$