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Finding the Fourth Proportional to 213.80, 320.64 and 85.52

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Solution

The fourth proportional to 213.80, 320.64 and 85.52 is: 128.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.80 : 320.64 = 85.52 : x
  2. Step 2: Convert to fraction form
    213.80/320.64 = 85.52/x
  3. Step 3: Cross multiply
    213.80x = 320.64 × 85.52
  4. Step 4: Simplify right side
    213.80x = 27,421.13
  5. Step 5: Solve for x
    x = 27,421.13/213.80
  6. Step 6: Final answer
    x = 128.26

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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.