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Finding the Fourth Proportional to 709.12, 1,063.68 and 420.64

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Solution

The fourth proportional to 709.12, 1,063.68 and 420.64 is: 630.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    709.12 : 1,063.68 = 420.64 : x
  2. Step 2: Convert to fraction form
    709.12/1,063.68 = 420.64/x
  3. Step 3: Cross multiply
    709.12x = 1,063.68 × 420.64
  4. Step 4: Simplify right side
    709.12x = 447,426.36
  5. Step 5: Solve for x
    x = 447,426.36/709.12
  6. Step 6: Final answer
    x = 630.96

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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.