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Finding the Fourth Proportional to 861.40, 1,291.63 and 340.87

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Solution

The fourth proportional to 861.40, 1,291.63 and 340.87 is: 511.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.40 : 1,291.63 = 340.87 : x
  2. Step 2: Convert to fraction form
    861.40/1,291.63 = 340.87/x
  3. Step 3: Cross multiply
    861.40x = 1,291.63 × 340.87
  4. Step 4: Simplify right side
    861.40x = 440,277.92
  5. Step 5: Solve for x
    x = 440,277.92/861.40
  6. Step 6: Final answer
    x = 511.12

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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.