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Finding the Fourth Proportional to 919.18, 1,378.50 and 431.74

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Solution

The fourth proportional to 919.18, 1,378.50 and 431.74 is: 647.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.18 : 1,378.50 = 431.74 : x
  2. Step 2: Convert to fraction form
    919.18/1,378.50 = 431.74/x
  3. Step 3: Cross multiply
    919.18x = 1,378.50 × 431.74
  4. Step 4: Simplify right side
    919.18x = 595,153.59
  5. Step 5: Solve for x
    x = 595,153.59/919.18
  6. Step 6: Final answer
    x = 647.48

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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.