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Finding the Fourth Proportional to 861.94, 1,288.97 and 642.72

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Solution

The fourth proportional to 861.94, 1,288.97 and 642.72 is: 961.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.94 : 1,288.97 = 642.72 : x
  2. Step 2: Convert to fraction form
    861.94/1,288.97 = 642.72/x
  3. Step 3: Cross multiply
    861.94x = 1,288.97 × 642.72
  4. Step 4: Simplify right side
    861.94x = 828,446.80
  5. Step 5: Solve for x
    x = 828,446.80/861.94
  6. Step 6: Final answer
    x = 961.14

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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.