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Finding the Fourth Proportional to 91.20, 121.20 and 91.20

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Solution

The fourth proportional to 91.20, 121.20 and 91.20 is: 121.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.20 : 121.20 = 91.20 : x
  2. Step 2: Convert to fraction form
    91.20/121.20 = 91.20/x
  3. Step 3: Cross multiply
    91.20x = 121.20 × 91.20
  4. Step 4: Simplify right side
    91.20x = 11,053.44
  5. Step 5: Solve for x
    x = 11,053.44/91.20
  6. Step 6: Final answer
    x = 121.20

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Why These Related Problems?

These problems maintain the same ratio (1.33) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.