Answer
a. $\frac{13}{18}$
b. $\frac{1}{6}$
c. $\frac{11}{36}$
Work Step by Step
a. A sum less than 9
There are 26 (11,12,13,14,15,16,21,22,23,24,25,26,31,32,33,34,35,41,42,43,44,51,52,53,61,62) favorable outcomes.
The total out comes are 36 $(6\times6)$. So the probability of getting a sum less than 9 is $p=\frac{26}{36}=\frac{13}{18}$
b. A sum greater than or equal to 10
There are 6 (46,55,56,64,65,66) favorable outcomes.
So the probability of getting a sum greater than or equal to 10 is $p=\frac{6}{36}=\frac{1}{6}$
c. A 3 on one die or on both dice.
There are 11 (13,23,31,32,33,34,35,36,43,53,63) favorable outcomes.
So the probability of getting a 3 on one die or on both dice is $p=\frac{11}{36}$