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Finding the Fourth Proportional to 80.68, 121.75 and 77.80

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Solution

The fourth proportional to 80.68, 121.75 and 77.80 is: 117.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.68 : 121.75 = 77.80 : x
  2. Step 2: Convert to fraction form
    80.68/121.75 = 77.80/x
  3. Step 3: Cross multiply
    80.68x = 121.75 × 77.80
  4. Step 4: Simplify right side
    80.68x = 9,472.15
  5. Step 5: Solve for x
    x = 9,472.15/80.68
  6. Step 6: Final answer
    x = 117.40

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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.