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Finding the Fourth Proportional to 8.58, 12.85 and 7.21

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Solution

The fourth proportional to 8.58, 12.85 and 7.21 is: 10.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    8.58 : 12.85 = 7.21 : x
  2. Step 2: Convert to fraction form
    8.58/12.85 = 7.21/x
  3. Step 3: Cross multiply
    8.58x = 12.85 × 7.21
  4. Step 4: Simplify right side
    8.58x = 92.58
  5. Step 5: Solve for x
    x = 92.58/8.58
  6. Step 6: Final answer
    x = 10.79

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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.