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Finding the Fourth Proportional to 81.43, 121.54 and 70.66

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Solution

The fourth proportional to 81.43, 121.54 and 70.66 is: 105.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.43 : 121.54 = 70.66 : x
  2. Step 2: Convert to fraction form
    81.43/121.54 = 70.66/x
  3. Step 3: Cross multiply
    81.43x = 121.54 × 70.66
  4. Step 4: Simplify right side
    81.43x = 8,588.02
  5. Step 5: Solve for x
    x = 8,588.02/81.43
  6. Step 6: Final answer
    x = 105.47

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.