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Finding the Fourth Proportional to 920, 1,380 and 868.64

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Solution

The fourth proportional to 920, 1,380 and 868.64 is: 1,302.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    920 : 1,380 = 868.64 : x
  2. Step 2: Convert to fraction form
    920/1,380 = 868.64/x
  3. Step 3: Cross multiply
    920x = 1,380 × 868.64
  4. Step 4: Simplify right side
    920x = 1,198,723.20
  5. Step 5: Solve for x
    x = 1,198,723.20/920
  6. Step 6: Final answer
    x = 1,302.96

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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.