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Finding the Fourth Proportional to 1,385.61, 2,078.51 and 411.78

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Solution

The fourth proportional to 1,385.61, 2,078.51 and 411.78 is: 617.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,385.61 : 2,078.51 = 411.78 : x
  2. Step 2: Convert to fraction form
    1,385.61/2,078.51 = 411.78/x
  3. Step 3: Cross multiply
    1,385.61x = 2,078.51 × 411.78
  4. Step 4: Simplify right side
    1,385.61x = 855,888.85
  5. Step 5: Solve for x
    x = 855,888.85/1,385.61
  6. Step 6: Final answer
    x = 617.70

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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.