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Finding the Fourth Proportional to 80.66, 121.05 and 56.78

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Solution

The fourth proportional to 80.66, 121.05 and 56.78 is: 85.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.66 : 121.05 = 56.78 : x
  2. Step 2: Convert to fraction form
    80.66/121.05 = 56.78/x
  3. Step 3: Cross multiply
    80.66x = 121.05 × 56.78
  4. Step 4: Simplify right side
    80.66x = 6,873.22
  5. Step 5: Solve for x
    x = 6,873.22/80.66
  6. Step 6: Final answer
    x = 85.21

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.