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Finding the Fourth Proportional to 918.45, 1,378.32 and 431.55

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Solution

The fourth proportional to 918.45, 1,378.32 and 431.55 is: 647.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.45 : 1,378.32 = 431.55 : x
  2. Step 2: Convert to fraction form
    918.45/1,378.32 = 431.55/x
  3. Step 3: Cross multiply
    918.45x = 1,378.32 × 431.55
  4. Step 4: Simplify right side
    918.45x = 594,814.00
  5. Step 5: Solve for x
    x = 594,814.00/918.45
  6. Step 6: Final answer
    x = 647.63

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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.