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Finding the Fourth Proportional to 80.40, 121.33 and 77.72

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Solution

The fourth proportional to 80.40, 121.33 and 77.72 is: 117.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.40 : 121.33 = 77.72 : x
  2. Step 2: Convert to fraction form
    80.40/121.33 = 77.72/x
  3. Step 3: Cross multiply
    80.40x = 121.33 × 77.72
  4. Step 4: Simplify right side
    80.40x = 9,429.77
  5. Step 5: Solve for x
    x = 9,429.77/80.40
  6. Step 6: Final answer
    x = 117.29

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.