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Finding the Fourth Proportional to 81.32, 121.40 and 70.52

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Solution

The fourth proportional to 81.32, 121.40 and 70.52 is: 105.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.32 : 121.40 = 70.52 : x
  2. Step 2: Convert to fraction form
    81.32/121.40 = 70.52/x
  3. Step 3: Cross multiply
    81.32x = 121.40 × 70.52
  4. Step 4: Simplify right side
    81.32x = 8,561.13
  5. Step 5: Solve for x
    x = 8,561.13/81.32
  6. Step 6: Final answer
    x = 105.28

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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.