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Finding the Fourth Proportional to 918.85, 1,378.74 and 431.83

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Solution

The fourth proportional to 918.85, 1,378.74 and 431.83 is: 647.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.85 : 1,378.74 = 431.83 : x
  2. Step 2: Convert to fraction form
    918.85/1,378.74 = 431.83/x
  3. Step 3: Cross multiply
    918.85x = 1,378.74 × 431.83
  4. Step 4: Simplify right side
    918.85x = 595,381.29
  5. Step 5: Solve for x
    x = 595,381.29/918.85
  6. Step 6: Final answer
    x = 647.96

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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.