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Finding the Fourth Proportional to 919.38, 1,378.91 and 261.30

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Solution

The fourth proportional to 919.38, 1,378.91 and 261.30 is: 391.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.38 : 1,378.91 = 261.30 : x
  2. Step 2: Convert to fraction form
    919.38/1,378.91 = 261.30/x
  3. Step 3: Cross multiply
    919.38x = 1,378.91 × 261.30
  4. Step 4: Simplify right side
    919.38x = 360,309.18
  5. Step 5: Solve for x
    x = 360,309.18/919.38
  6. Step 6: Final answer
    x = 391.90

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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.