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Finding the Fourth Proportional to 81.34, 111.90 and 72.16

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Solution

The fourth proportional to 81.34, 111.90 and 72.16 is: 99.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.34 : 111.90 = 72.16 : x
  2. Step 2: Convert to fraction form
    81.34/111.90 = 72.16/x
  3. Step 3: Cross multiply
    81.34x = 111.90 × 72.16
  4. Step 4: Simplify right side
    81.34x = 8,074.70
  5. Step 5: Solve for x
    x = 8,074.70/81.34
  6. Step 6: Final answer
    x = 99.27

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.