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Finding the Fourth Proportional to 8.57, 12.88 and 5.20

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Solution

The fourth proportional to 8.57, 12.88 and 5.20 is: 7.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    8.57 : 12.88 = 5.20 : x
  2. Step 2: Convert to fraction form
    8.57/12.88 = 5.20/x
  3. Step 3: Cross multiply
    8.57x = 12.88 × 5.20
  4. Step 4: Simplify right side
    8.57x = 66.98
  5. Step 5: Solve for x
    x = 66.98/8.57
  6. Step 6: Final answer
    x = 7.82

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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.