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Finding the Fourth Proportional to 815.47, 1,221.89 and 424.89

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Solution

The fourth proportional to 815.47, 1,221.89 and 424.89 is: 636.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.47 : 1,221.89 = 424.89 : x
  2. Step 2: Convert to fraction form
    815.47/1,221.89 = 424.89/x
  3. Step 3: Cross multiply
    815.47x = 1,221.89 × 424.89
  4. Step 4: Simplify right side
    815.47x = 519,166.72
  5. Step 5: Solve for x
    x = 519,166.72/815.47
  6. Step 6: Final answer
    x = 636.65

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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.