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Finding the Fourth Proportional to 81.58, 122.45 and 47.40

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Solution

The fourth proportional to 81.58, 122.45 and 47.40 is: 71.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.58 : 122.45 = 47.40 : x
  2. Step 2: Convert to fraction form
    81.58/122.45 = 47.40/x
  3. Step 3: Cross multiply
    81.58x = 122.45 × 47.40
  4. Step 4: Simplify right side
    81.58x = 5,804.58
  5. Step 5: Solve for x
    x = 5,804.58/81.58
  6. Step 6: Final answer
    x = 71.16

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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.