A box contains 100 red cards, 200 yellow cards and 50 blue cards. If a card is drawn at random from the box, then find the probability that it will be a blue card.

Given:

A box contains 100 red cards, 200 yellow cards and 50 blue cards.

A card is drawn at random from the box.

To do:

We have to find the probability that it will be a blue card.

Solution:

Number of red cards $=100$

Number of yellow cards $=200$

Number of blue cards $=50$

This implies,

The total number of cards $=100+200+50=350$

The total number of possible outcomes $n=350$.

Total number of favourable outcomes $=50$.

We know that,

Probability of an event $=\frac{Number\ of\ favourable\ outcomes}{Total\ number\ of\ possible\ outcomes}$

Therefore,

Probability that it will be a blue card $=\frac{50}{350}$

$=\frac{1}{7}$

The probability that it will be a blue card is $\frac{1}{7}$.