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Finding the Fourth Proportional to 80.94, 121.35 and 39.78

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Solution

The fourth proportional to 80.94, 121.35 and 39.78 is: 59.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.94 : 121.35 = 39.78 : x
  2. Step 2: Convert to fraction form
    80.94/121.35 = 39.78/x
  3. Step 3: Cross multiply
    80.94x = 121.35 × 39.78
  4. Step 4: Simplify right side
    80.94x = 4,827.30
  5. Step 5: Solve for x
    x = 4,827.30/80.94
  6. Step 6: Final answer
    x = 59.64

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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.