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Finding the Fourth Proportional to 813.80, 1,220.59 and 319.87

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Solution

The fourth proportional to 813.80, 1,220.59 and 319.87 is: 479.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.80 : 1,220.59 = 319.87 : x
  2. Step 2: Convert to fraction form
    813.80/1,220.59 = 319.87/x
  3. Step 3: Cross multiply
    813.80x = 1,220.59 × 319.87
  4. Step 4: Simplify right side
    813.80x = 390,423.38
  5. Step 5: Solve for x
    x = 390,423.38/813.80
  6. Step 6: Final answer
    x = 479.76

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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.