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Finding the Fourth Proportional to 809.42, 1,211.65 and 653.90

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Solution

The fourth proportional to 809.42, 1,211.65 and 653.90 is: 978.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    809.42 : 1,211.65 = 653.90 : x
  2. Step 2: Convert to fraction form
    809.42/1,211.65 = 653.90/x
  3. Step 3: Cross multiply
    809.42x = 1,211.65 × 653.90
  4. Step 4: Simplify right side
    809.42x = 792,297.94
  5. Step 5: Solve for x
    x = 792,297.94/809.42
  6. Step 6: Final answer
    x = 978.85

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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.