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Finding the Fourth Proportional to 1,388.90, 2,081.72 and 648.92

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Solution

The fourth proportional to 1,388.90, 2,081.72 and 648.92 is: 972.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,388.90 : 2,081.72 = 648.92 : x
  2. Step 2: Convert to fraction form
    1,388.90/2,081.72 = 648.92/x
  3. Step 3: Cross multiply
    1,388.90x = 2,081.72 × 648.92
  4. Step 4: Simplify right side
    1,388.90x = 1,350,869.74
  5. Step 5: Solve for x
    x = 1,350,869.74/1,388.90
  6. Step 6: Final answer
    x = 972.62

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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.