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Finding the Fourth Proportional to 80.76, 121.64 and 78.04

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Solution

The fourth proportional to 80.76, 121.64 and 78.04 is: 117.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.76 : 121.64 = 78.04 : x
  2. Step 2: Convert to fraction form
    80.76/121.64 = 78.04/x
  3. Step 3: Cross multiply
    80.76x = 121.64 × 78.04
  4. Step 4: Simplify right side
    80.76x = 9,492.79
  5. Step 5: Solve for x
    x = 9,492.79/80.76
  6. Step 6: Final answer
    x = 117.54

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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.