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Finding the Fourth Proportional to 209.24, 313.85 and 85.80

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Solution

The fourth proportional to 209.24, 313.85 and 85.80 is: 128.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.24 : 313.85 = 85.80 : x
  2. Step 2: Convert to fraction form
    209.24/313.85 = 85.80/x
  3. Step 3: Cross multiply
    209.24x = 313.85 × 85.80
  4. Step 4: Simplify right side
    209.24x = 26,927.90
  5. Step 5: Solve for x
    x = 26,927.90/209.24
  6. Step 6: Final answer
    x = 128.70

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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.