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Finding the Fourth Proportional to 81.56, 121.70 and 79.22

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Solution

The fourth proportional to 81.56, 121.70 and 79.22 is: 118.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.56 : 121.70 = 79.22 : x
  2. Step 2: Convert to fraction form
    81.56/121.70 = 79.22/x
  3. Step 3: Cross multiply
    81.56x = 121.70 × 79.22
  4. Step 4: Simplify right side
    81.56x = 9,641.07
  5. Step 5: Solve for x
    x = 9,641.07/81.56
  6. Step 6: Final answer
    x = 118.21

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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.