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Finding the Fourth Proportional to 813.90, 1,220.04 and 319.92

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Solution

The fourth proportional to 813.90, 1,220.04 and 319.92 is: 479.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.90 : 1,220.04 = 319.92 : x
  2. Step 2: Convert to fraction form
    813.90/1,220.04 = 319.92/x
  3. Step 3: Cross multiply
    813.90x = 1,220.04 × 319.92
  4. Step 4: Simplify right side
    813.90x = 390,315.20
  5. Step 5: Solve for x
    x = 390,315.20/813.90
  6. Step 6: Final answer
    x = 479.56

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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.