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Finding the Fourth Proportional to 1,421.91, 2,131.11 and 641.69

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Solution

The fourth proportional to 1,421.91, 2,131.11 and 641.69 is: 961.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,421.91 : 2,131.11 = 641.69 : x
  2. Step 2: Convert to fraction form
    1,421.91/2,131.11 = 641.69/x
  3. Step 3: Cross multiply
    1,421.91x = 2,131.11 × 641.69
  4. Step 4: Simplify right side
    1,421.91x = 1,367,507.72
  5. Step 5: Solve for x
    x = 1,367,507.72/1,421.91
  6. Step 6: Final answer
    x = 961.74

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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.