Question

sum of digits of a 2-digit number is 9 find the probability that such a number is (a) not even (b) odd composite no (c) divisible by 3

Answer 1

Dear Student,

Sum of digits of a two digit number is 9.
So, possible outcomes are 18, 27, 36, 45, 54, 63, 72, 81, 90. Total possible outcomes $=9$.
(a) Odd numbers are (27, 45, 63, 81) = 4
Probability of a number which is not even $=\frac{4}{9}$
(b) Odd composite numbers are (27, 45, 63, 81) = 4
Probability of an odd composite number $=\frac{4}{9}$
(c) Numbers divisible by 3 are (18, 27, 36, 45, 54, 63, 72, 81, 90) = 9
Probability of a number divisible by 3 $=\frac{9}{9}=1$
Regards,