Make up a set of at least 12 numbers that have the following landmarks maximum 18 range 13 mode 7 and median 12

Start with maximum 18.

Range is 13, so minimum is 5.
Median is 12, so you'd be safe to put 12 (or 11 and 13) in the 6th and 7th place to get:
5 * * * * 12 12 * * * * 18, or
5 * * * * 11 13 * * * * 18.

All you need to do is to insert numbers so that the mode is 7. The mean is not specified, so you can put anything in the rest (but keeping the mode at 7).

To create a set of numbers with the given landmarks, maximum 18, range 13, mode 7, and median 12, we can use the following steps:

1. Start by finding the maximum value. Since the maximum value should be 18, we can include 18 as one of the numbers.

2. Next, determine the range. The range is the difference between the maximum and minimum values. In this case, the range should be 13. Since we have already included the maximum value of 18, the minimum value would be 18 - 13 = 5.

3. Now, let's determine the mode. The mode is the value that appears most frequently in a set of numbers. In this case, the mode should be 7. We need to choose at least two numbers that are 7 in our set.

4. Finally, we need to determine the median. The median is the middle value when the numbers are arranged in ascending order. In this case, the median should be 12. To achieve this, we will need to arrange our set of numbers accordingly.

Following these guidelines, we can create a set of numbers with the given landmarks:

{5, 5, 7, 7, 8, 9, 9, 10, 11, 12, 12, 12, 18}

In this set, the maximum value is 18, the range is 13, the mode is 7, and the median is 12.