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Finding the Fourth Proportional to 7.85, 10.89 and 7.31

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Solution

The fourth proportional to 7.85, 10.89 and 7.31 is: 10.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    7.85 : 10.89 = 7.31 : x
  2. Step 2: Convert to fraction form
    7.85/10.89 = 7.31/x
  3. Step 3: Cross multiply
    7.85x = 10.89 × 7.31
  4. Step 4: Simplify right side
    7.85x = 79.61
  5. Step 5: Solve for x
    x = 79.61/7.85
  6. Step 6: Final answer
    x = 10.14

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.