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Finding the Fourth Proportional to 667.12, 920.64 and 391.12

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Solution

The fourth proportional to 667.12, 920.64 and 391.12 is: 539.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    667.12 : 920.64 = 391.12 : x
  2. Step 2: Convert to fraction form
    667.12/920.64 = 391.12/x
  3. Step 3: Cross multiply
    667.12x = 920.64 × 391.12
  4. Step 4: Simplify right side
    667.12x = 360,080.72
  5. Step 5: Solve for x
    x = 360,080.72/667.12
  6. Step 6: Final answer
    x = 539.75

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.