1. **Problem statement:** We are given the ordered numbers: $x$, $(x + 1)$, $5$, $(2x + 1)$, $(y + 2)$, $7$, $8$, and $(3x + 2)$. The mean of these numbers is 6.5, and the median is 7. We need to find the values of $x$ and $y$.
2. **Formula for mean:**
$$\text{Mean} = \frac{\text{Sum of all numbers}}{\text{Number of numbers}}$$
3. **Calculate the sum using the mean:**
There are 8 numbers, so:
$$\frac{x + (x+1) + 5 + (2x+1) + (y+2) + 7 + 8 + (3x+2)}{8} = 6.5$$
Multiply both sides by 8:
$$x + (x+1) + 5 + (2x+1) + (y+2) + 7 + 8 + (3x+2) = 52$$
4. **Simplify the sum:**
Combine like terms:
$$x + x + 1 + 5 + 2x + 1 + y + 2 + 7 + 8 + 3x + 2 = 52$$
Group $x$ terms:
$$x + x + 2x + 3x = 7x$$
Constants:
$$1 + 5 + 1 + 2 + 7 + 8 + 2 = 26$$
So the equation becomes:
$$7x + y + 26 = 52$$
Subtract 26 from both sides:
$$7x + y = 26$$
5. **Median condition:**
The median of 8 numbers is the average of the 4th and 5th numbers when the numbers are ordered.
Median = 7, so:
$$\frac{\text{4th number} + \text{5th number}}{2} = 7$$
$$\text{4th number} + \text{5th number} = 14$$
6. **Order the numbers to find the 4th and 5th:**
The numbers are:
$$x, x+1, 5, 2x+1, y+2, 7, 8, 3x+2$$
We need to find $x$ and $y$ such that the median is 7.
7. **Assuming $x$ is such that the numbers in order place 7 as median:**
Try to find $x$ so that the 4th and 5th numbers sum to 14.
8. **Try $x=2$:**
Calculate numbers:
$$2, 3, 5, 5, y+2, 7, 8, 8$$
Order:
$$2, 3, 5, 5, 7, 8, 8, y+2$$
If $y+2$ is greater than 8, the 4th and 5th numbers are 5 and 7, sum 12, not 14.
9. **Try $x=3$:**
Numbers:
$$3, 4, 5, 7, y+2, 7, 8, 11$$
Order:
$$3, 4, 5, 7, 7, 8, 11, y+2$$
If $y+2$ is greater than 11, 4th and 5th numbers are 7 and 7, sum 14, median 7.
10. **Use equation from step 4:**
$$7x + y = 26$$
Substitute $x=3$:
$$7(3) + y = 26$$
$$21 + y = 26$$
$$y = 5$$
11. **Check $y+2$:**
$$5 + 2 = 7$$
So the numbers are:
$$3, 4, 5, 7, 7, 7, 8, 11$$
Ordered:
$$3, 4, 5, 7, 7, 7, 8, 11$$
4th and 5th numbers are both 7, median is 7.
12. **Final answer:**
$$x = 3, \quad y = 5$$
Mean Median Values 1691Dd
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