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Finding the Fourth Proportional to 81.15, 111.90 and 51.63

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Solution

The fourth proportional to 81.15, 111.90 and 51.63 is: 71.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.15 : 111.90 = 51.63 : x
  2. Step 2: Convert to fraction form
    81.15/111.90 = 51.63/x
  3. Step 3: Cross multiply
    81.15x = 111.90 × 51.63
  4. Step 4: Simplify right side
    81.15x = 5,777.17
  5. Step 5: Solve for x
    x = 5,777.17/81.15
  6. Step 6: Final answer
    x = 71.19

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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.