From

    \[\mathbf{25}\]

identical cards,

    \[\text{ }\mathbf{1},\text{ }\mathbf{2},\text{ }\mathbf{3},\text{ }\mathbf{4},\text{ }\mathbf{5},\text{ }\ldots \ldots ,~\mathbf{24},\text{ }\mathbf{25}:\]

numbered one card is drawn at random. Find the probability that the number on the card drawn is a multiple of

    \[\left( \mathbf{i} \right)\text{ }\mathbf{3}\]

    \[\left( \mathbf{ii} \right)\text{ }\mathbf{5}\]

From

    \[\mathbf{25}\]

identical cards,

    \[\text{ }\mathbf{1},\text{ }\mathbf{2},\text{ }\mathbf{3},\text{ }\mathbf{4},\text{ }\mathbf{5},\text{ }\ldots \ldots ,~\mathbf{24},\text{ }\mathbf{25}:\]

numbered one card is drawn at random. Find the probability that the number on the card drawn is a multiple of

    \[\left( \mathbf{i} \right)\text{ }\mathbf{3}\]

    \[\left( \mathbf{ii} \right)\text{ }\mathbf{5}\]

Solution:

We know that, there are

    \[25\]

cards from which one card is drawn.

So, the total number of elementary events

    \[=\text{ }n\left( S \right)\text{ }=\text{ }25\]

    \[\left( i \right)\]

From numbers

    \[1\text{ }to\text{ }25\]

, there are

    \[8\]

numbers which are multiple of

    \[3\text{ }i.e.~\{3,\text{ }6,\text{ }9,\text{ }12,\text{ }15,\text{ }18\]

,

    \[~21,\text{ }24\}\]

So, favorable number of events

    \[=\text{ }n\left( E \right)\text{ }=\text{ }8\]

Hence, probability of selecting a card with a multiple of

    \[3\text{ }=\text{ }n\left( E \right)/\text{ }n\left( S \right)\text{ }=\text{ }8/25\]

    \[\left( ii \right)\]

From numbers

    \[1\text{ }to\text{ }25\]

, there are

    \[5\]

numbers which are multiple of

    \[5\text{ }i.e.~\left\{ 5,\text{ }10,\text{ }15,\text{ }20,\text{ }25 \right\}\]

So, favorable number of events

    \[=\text{ }n\left( E \right)\text{ }=\text{ }5\]

Hence, probability of selecting a card with a multiple of

    \[5\text{ }=\text{ }n\left( E \right)/\text{ }n\left( S \right)\text{ }=\text{ }5/25\text{ }=\text{ }1/5\]