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Finding the Fourth Proportional to 860.67, 1,291 and 312.85

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Solution

The fourth proportional to 860.67, 1,291 and 312.85 is: 469.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.67 : 1,291 = 312.85 : x
  2. Step 2: Convert to fraction form
    860.67/1,291 = 312.85/x
  3. Step 3: Cross multiply
    860.67x = 1,291 × 312.85
  4. Step 4: Simplify right side
    860.67x = 403,889.35
  5. Step 5: Solve for x
    x = 403,889.35/860.67
  6. Step 6: Final answer
    x = 469.27

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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.