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Finding the Fourth Proportional to 1,069.72, 1,604.40 and 420.64

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Solution

The fourth proportional to 1,069.72, 1,604.40 and 420.64 is: 630.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,069.72 : 1,604.40 = 420.64 : x
  2. Step 2: Convert to fraction form
    1,069.72/1,604.40 = 420.64/x
  3. Step 3: Cross multiply
    1,069.72x = 1,604.40 × 420.64
  4. Step 4: Simplify right side
    1,069.72x = 674,874.82
  5. Step 5: Solve for x
    x = 674,874.82/1,069.72
  6. Step 6: Final answer
    x = 630.89

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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.