Question

A number is selected at random from the numbers: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11....................... 95, 96, 97, 98, 99, 100. What is the probability that the sum of digits of the selected number is 10?

• A. 0.9
• B. 0.09
• C. 0.1
• D. 0.01

Answer 1

The correct option is B 0.09

Total no. of outcomes (count of numbers from 1 to 100) = 100
Favourable outcomes (the sum of the digits is '10 ') are: 19,28,37,46,55,64,73,82 and 91
$\therefore$ Total no. of favourable outcomes = 9

Let $E$ be the event of getting a number whose sum of digits is 10.

$\text{Probability P(E)}$ = $\frac{\text{Number of outcomes favorable to E}}{\text{Number of all possible outcomes of the experiment}}$

P(Sum of the digits is 10)
$=\frac{9}{100}=0.09$