Consider all four-digit numbers that can be made from the digits 0-8 (assume that numbers cannot start with 0). What is the probability of choosing a random number from this group that is less than or equal to 4000

The probability is:

P = 0.375

Step-by-step explanation:

First, we need to find the total number of four-digit numbers that can be made with the digits 0-8, such that the first digit can not be zero.

To do this, we first need to find the number of selections that we have, in this case, there are 4, one for each digit in our 4-digit number.

Now let's count the number of options that we have for each one of these selections:

first digit: we have 8 options (because the 0 can not be here)

second digit: we have 9 options (because now the zero can be taken)

third digit: we have 9 options

fourth digit: we have 9 options.

The total number of combinations is equal to the product of all the numbers of options, this is:

C = 8*9*9*9 = 5,832

Now we need to find how many of these are less or equal than 4000.

So now let's count the options again:

first digit: 3 options {1, 2, 3}

second digit: 9 options

third digit: 9 option

fourth digit: 9 options

Total number of combinations:

C' = 3*9*9*9 = 2,187

Here we should also count the combination for the number 4000 itself, as it was not counted in our previous calculation, then we have:

C' = 2,187 + 1 = 2,188 combinations.

The probability of randomly choosing a number that is smaller than or equal to 4000 will be equal to the quotient between the number of combinations that are smaller than or equal to 4000 (2,188 combinations) and the total number of combinations (5,832)

this is:

P = 2,188/5,832 = 0.375