There are 5 slots, each containing the letters w, r, l, d or o. one letter is picked at random from each slot. what are the odds that the letters stored in these slots read the word world?

In the first slot lets calculate the chance of getting a w: 1/5

In the second slot calculate the chance of getting a o: 1/4 (notice how it's 4 not 5 because you already have one letter in the first slot so you have 4 left to choose from.)

In third slot, chance of getting a r: 1/3

In fourth slot, chance of getting a l: 1/2

In the fifth slot, if you got all the first four letters right, than you would be left with one letter, so your chances are 1/1 (100%) for the fifth slot

To calculate probability multiply all the fractions we got above: 1/5 x 1/4 x 1/3 x 1/2 x 1/1

We will then get: 1/(5x4x3x2x1) = 1/120

1/120 is the probability of the 5 slots showing the word "world"