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Finding the Fourth Proportional to 213.12, 320 and 172.80

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Solution

The fourth proportional to 213.12, 320 and 172.80 is: 259.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.12 : 320 = 172.80 : x
  2. Step 2: Convert to fraction form
    213.12/320 = 172.80/x
  3. Step 3: Cross multiply
    213.12x = 320 × 172.80
  4. Step 4: Simplify right side
    213.12x = 55,296
  5. Step 5: Solve for x
    x = 55,296/213.12
  6. Step 6: Final answer
    x = 259.46

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.