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Finding the Fourth Proportional to 142.51, 213.80 and 81.68

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Solution

The fourth proportional to 142.51, 213.80 and 81.68 is: 122.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.51 : 213.80 = 81.68 : x
  2. Step 2: Convert to fraction form
    142.51/213.80 = 81.68/x
  3. Step 3: Cross multiply
    142.51x = 213.80 × 81.68
  4. Step 4: Simplify right side
    142.51x = 17,463.18
  5. Step 5: Solve for x
    x = 17,463.18/142.51
  6. Step 6: Final answer
    x = 122.54

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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.