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Finding the Fourth Proportional to 919.13, 1,378.92 and 431.62

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Solution

The fourth proportional to 919.13, 1,378.92 and 431.62 is: 647.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.13 : 1,378.92 = 431.62 : x
  2. Step 2: Convert to fraction form
    919.13/1,378.92 = 431.62/x
  3. Step 3: Cross multiply
    919.13x = 1,378.92 × 431.62
  4. Step 4: Simplify right side
    919.13x = 595,169.45
  5. Step 5: Solve for x
    x = 595,169.45/919.13
  6. Step 6: Final answer
    x = 647.54

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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.