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Finding the Fourth Proportional to 2,118.78, 3,178.21 and 657.89

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Solution

The fourth proportional to 2,118.78, 3,178.21 and 657.89 is: 986.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,118.78 : 3,178.21 = 657.89 : x
  2. Step 2: Convert to fraction form
    2,118.78/3,178.21 = 657.89/x
  3. Step 3: Cross multiply
    2,118.78x = 3,178.21 × 657.89
  4. Step 4: Simplify right side
    2,118.78x = 2,090,909.29
  5. Step 5: Solve for x
    x = 2,090,909.29/2,118.78
  6. Step 6: Final answer
    x = 986.85

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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.