Number Frac Shape
1. **Identify the integers and mixed numbers in the list:**
The list contains: $-15\frac{2}{3},\;0,\;21,\;-20,\;15\frac{1}{3},\;-1$.
2. **Determine the largest value:**
From the numbers, $21$ is the largest as it is the only positive integer greater than any fractional mixed number in the list.
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3. **Find the number halfway between $-2\frac{1}{2}$ and $3$:**
Step 1: Convert mixed number to improper fraction or decimal:
$-2\frac{1}{2} = -2.5$
Step 2: Calculate midpoint
definition:
Halfway number = $\frac{-2.5 + 3}{2} = \frac{0.5}{2} = 0.25$
So, the number halfway between $-2\frac{1}{2}$ and $3$ is $0.25$.
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4. **Analyze the shaded and unshaded areas in the 10x10 grid:**
- Total squares = $10 \times 10 = 100$
- The shaded layers are:
- Outermost border: $10 \times 10$ square border = outer ring (width 1), count = $10 \times 10 - 8 \times 8 = 100 - 64 = 36$ squares
- Next shaded border inside (1 square wide), after unshaded border:
- Second shaded border ring: between $8 \times 8$ and $6 \times 6$, count = $8 \times 8 - 6 \times 6 = 64 - 36 = 28$ squares
- Central shaded area is $4 \times 4 = 16$ squares
- Total shaded squares = $36 + 28 + 16 = 80$
- Fraction shaded = $\frac{80}{100} = \frac{4}{5}$
5. **Fraction of unshaded area on the outer border:**
- Total unshaded squares = total - shaded = $100 - 80 = 20$
- Outer unshaded border is the one between outer shaded border (10x10) and next shaded border starts from 8x8 (but given unshaded border widths):
The unshaded borders are 1 square wide each, so the outer unshaded border lies between the outermost shaded border (10x10) and the next shaded border (8x8 to 6x6).
- Count of outer unshaded border = $8 \times 8 - 6 \times 6 = 64 - 36 = 28$, but this conflicts with the description, so more careful breakdown:
The grid layers are:
- First shaded border: 10x10 thin border (width 1): 36 squares (as above)
- Then unshaded border 1 square wide inside: area from 9x9 down to 8x8 (because 10x10 outer border - inner 8x8 second shaded border—unshaded border must be just 1-square wide ring between 9x9 and 8x8, so unshaded border squares = $9 \times 9 - 8 \times 8 = 81 -64 =17$ squares
- Next shaded border: 8x8 to 6x6 ring: $64 - 36 = 28$ squares
- Inner unshaded border: 7x7 to 6x6 ring: $49 - 36 = 13$ squares
- Central shaded area: $4x4=16$ squares
- Total shaded remains: $36 + 28 + 16=80$
- Total unshaded: $17 + 13 = 30$ squares
- Fraction unshaded: $\frac{30}{100} = \frac{3}{10}$
- Out of the unshaded 30 squares, the outer border unshaded is 17 squares
- Fraction of unshaded area on outer border = $\frac{17}{30}$
**Final answers:**
- Largest number in list: $21$
- Number halfway between $-2\frac{1}{2}$ and $3$: $0.25$
- Fraction of shape shaded: $\frac{4}{5}$
- Fraction of unshaded area on outer border: $\frac{17}{30}$