A bag contains n cards, each having one of the consecutive numbers (1, 2, 3, 4, .... n) written on it, with each number being used once. The probability of drawing a card with a number less than or equal to 10 is 4/10. How many cards are in the bag?

ten, of course.

25 To solve this problem, we need to set up an equation based on the given information.

Let's assume that the total number of cards in the bag is n.

We are told that the probability of drawing a card with a number less than or equal to 10 is 4/10.

The numbers from 1 to 10 are inclusive, so the probability of drawing any of these numbers is 10/n (out of n cards).

We can now set up the equation:

10/n = 4/10

To solve for n, we cross-multiply:

10 * 10 = 4 * n

100 = 4n

Divide both sides by 4:

n = 100/4

n = 25

Therefore, there are 25 cards in the bag.