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Finding the Fourth Proportional to 806.34, 1,209.78 and 319.72

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Solution

The fourth proportional to 806.34, 1,209.78 and 319.72 is: 479.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    806.34 : 1,209.78 = 319.72 : x
  2. Step 2: Convert to fraction form
    806.34/1,209.78 = 319.72/x
  3. Step 3: Cross multiply
    806.34x = 1,209.78 × 319.72
  4. Step 4: Simplify right side
    806.34x = 386,790.86
  5. Step 5: Solve for x
    x = 386,790.86/806.34
  6. Step 6: Final answer
    x = 479.69

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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.