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Finding the Fourth Proportional to 860.75, 1,291.09 and 421.87

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Solution

The fourth proportional to 860.75, 1,291.09 and 421.87 is: 632.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.75 : 1,291.09 = 421.87 : x
  2. Step 2: Convert to fraction form
    860.75/1,291.09 = 421.87/x
  3. Step 3: Cross multiply
    860.75x = 1,291.09 × 421.87
  4. Step 4: Simplify right side
    860.75x = 544,672.14
  5. Step 5: Solve for x
    x = 544,672.14/860.75
  6. Step 6: Final answer
    x = 632.79

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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.