Question

One ticket is selected at random from 100 tickets numbered 00, 01, 02....., 99. Suppose $X$ and $Y$ are the sum and product of the digit found on the ticket $P\left(\frac{Y=0}{X=7}\right)$ is given by

• A. $\frac{2}{3}$
• B. $\frac{1}{4}$
• C. $\frac{1}{50}$
• D. $\frac{3}{19}$

Answer 1

The correct option is B $\frac{1}{4}$

$X=7$ can be done in the following ways: $07,16,25,34,43,52,61,70$ i.e. $8$ ways.
Of these, $Y=0$ is possible when the number is $07$ or $70$ i.e. $2$ ways.
Probability = $\frac{2}{8}=\frac{1}{4}$