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Finding the Fourth Proportional to 213.80, 320.74 and 85.55

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Solution

The fourth proportional to 213.80, 320.74 and 85.55 is: 128.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    213.80 : 320.74 = 85.55 : x
  2. Step 2: Convert to fraction form
    213.80/320.74 = 85.55/x
  3. Step 3: Cross multiply
    213.80x = 320.74 × 85.55
  4. Step 4: Simplify right side
    213.80x = 27,437.49
  5. Step 5: Solve for x
    x = 27,437.49/213.80
  6. Step 6: Final answer
    x = 128.34

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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.