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Finding the Fourth Proportional to 813.68, 1,221.60 and 489.68

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Solution

The fourth proportional to 813.68, 1,221.60 and 489.68 is: 735.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.68 : 1,221.60 = 489.68 : x
  2. Step 2: Convert to fraction form
    813.68/1,221.60 = 489.68/x
  3. Step 3: Cross multiply
    813.68x = 1,221.60 × 489.68
  4. Step 4: Simplify right side
    813.68x = 598,193.09
  5. Step 5: Solve for x
    x = 598,193.09/813.68
  6. Step 6: Final answer
    x = 735.17

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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.