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Finding the Fourth Proportional to 920.40, 1,379.16 and 642.96

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Solution

The fourth proportional to 920.40, 1,379.16 and 642.96 is: 963.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.40 : 1,379.16 = 642.96 : x
  2. Step 2: Convert to fraction form
    920.40/1,379.16 = 642.96/x
  3. Step 3: Cross multiply
    920.40x = 1,379.16 × 642.96
  4. Step 4: Simplify right side
    920.40x = 886,744.71
  5. Step 5: Solve for x
    x = 886,744.71/920.40
  6. Step 6: Final answer
    x = 963.43

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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.