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Finding the Fourth Proportional to 1,212.13, 1,818.42 and 390.41

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Solution

The fourth proportional to 1,212.13, 1,818.42 and 390.41 is: 585.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,212.13 : 1,818.42 = 390.41 : x
  2. Step 2: Convert to fraction form
    1,212.13/1,818.42 = 390.41/x
  3. Step 3: Cross multiply
    1,212.13x = 1,818.42 × 390.41
  4. Step 4: Simplify right side
    1,212.13x = 709,929.35
  5. Step 5: Solve for x
    x = 709,929.35/1,212.13
  6. Step 6: Final answer
    x = 585.69

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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.