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Finding the Fourth Proportional to 613.80, 918.54 and 421.56

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Solution

The fourth proportional to 613.80, 918.54 and 421.56 is: 630.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    613.80 : 918.54 = 421.56 : x
  2. Step 2: Convert to fraction form
    613.80/918.54 = 421.56/x
  3. Step 3: Cross multiply
    613.80x = 918.54 × 421.56
  4. Step 4: Simplify right side
    613.80x = 387,219.72
  5. Step 5: Solve for x
    x = 387,219.72/613.80
  6. Step 6: Final answer
    x = 630.86

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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.