There are 25 red marbles and 75 blue marbles in a bag. You randomly pick one marble from the bag and then put it back. What is the probability of picking a red marble twice in a row?
Let's break down the problem into steps:

1. The probability of picking a red marble on the first try is 25/100 or 1/4 since there are 25 red marbles and a total of 100 marbles.
2. Since you're putting the marble back after the first pick, the probabilities remain the same for the second pick.
3. Therefore, the probability of picking a red marble on the second try is also 1/4.
4. To find the probability of both events happening together (picking a red marble twice in a row), we multiply their individual probabilities: (1/4) * (1/4) = 1/16.

The probability of picking a red marble twice in a row is 1/16.