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Finding the Fourth Proportional to 1,115.32, 1,671.70 and 421.40

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Solution

The fourth proportional to 1,115.32, 1,671.70 and 421.40 is: 631.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,115.32 : 1,671.70 = 421.40 : x
  2. Step 2: Convert to fraction form
    1,115.32/1,671.70 = 421.40/x
  3. Step 3: Cross multiply
    1,115.32x = 1,671.70 × 421.40
  4. Step 4: Simplify right side
    1,115.32x = 704,454.38
  5. Step 5: Solve for x
    x = 704,454.38/1,115.32
  6. Step 6: Final answer
    x = 631.62

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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.