probability of first number being even : 5 even numbers...10 equal sections...probability is 5/10 or 1/2
probability of 2nd number being odd : 5 odd numbers...10 equal sections...so probability of both is 5/10 or 1/2
probability of both occurring : 1/2 * 1/2 = 1/4 <== (or 25% if u need it in percent form or 0.25 if u need it in decimal form)