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Finding the Fourth Proportional to 81.47, 122.21 and 45.39

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Solution

The fourth proportional to 81.47, 122.21 and 45.39 is: 68.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.47 : 122.21 = 45.39 : x
  2. Step 2: Convert to fraction form
    81.47/122.21 = 45.39/x
  3. Step 3: Cross multiply
    81.47x = 122.21 × 45.39
  4. Step 4: Simplify right side
    81.47x = 5,547.51
  5. Step 5: Solve for x
    x = 5,547.51/81.47
  6. Step 6: Final answer
    x = 68.09

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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.