**Problem Statement:**
A bag contains 5 red balls and some blue balls. The probability of drawing a blue ball is double the probability of drawing a red ball. We need to determine the number of blue balls in the bag.

**Solution:**

Let's assume the number of blue balls in the bag is 'x'.

**Probability of drawing a blue ball:**
The probability of drawing a blue ball can be calculated by dividing the number of blue balls by the total number of balls in the bag.

P(blue ball) = (number of blue balls) / (total number of balls)

**Probability of drawing a red ball:**
The probability of drawing a red ball can be calculated by dividing the number of red balls by the total number of balls in the bag.

P(red ball) = (number of red balls) / (total number of balls)

According to the given information, the probability of drawing a blue ball is double the probability of drawing a red ball.

P(blue ball) = 2 * P(red ball)

(number of blue balls) / (total number of balls) = 2 * (number of red balls) / (total number of balls)

Simplifying the equation, we get:

(number of blue balls) = 2 * (number of red balls)

We are given that there are 5 red balls in the bag. Substituting this value into the equation, we have:

(number of blue balls) = 2 * 5

(number of blue balls) = 10

Therefore, there are 10 blue balls in the bag.