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Finding the Fourth Proportional to 81.42, 121.85 and 61.03

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Solution

The fourth proportional to 81.42, 121.85 and 61.03 is: 91.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.42 : 121.85 = 61.03 : x
  2. Step 2: Convert to fraction form
    81.42/121.85 = 61.03/x
  3. Step 3: Cross multiply
    81.42x = 121.85 × 61.03
  4. Step 4: Simplify right side
    81.42x = 7,436.51
  5. Step 5: Solve for x
    x = 7,436.51/81.42
  6. Step 6: Final answer
    x = 91.34

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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.