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Finding the Fourth Proportional to 80.64, 121.68 and 77.31

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Solution

The fourth proportional to 80.64, 121.68 and 77.31 is: 116.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.64 : 121.68 = 77.31 : x
  2. Step 2: Convert to fraction form
    80.64/121.68 = 77.31/x
  3. Step 3: Cross multiply
    80.64x = 121.68 × 77.31
  4. Step 4: Simplify right side
    80.64x = 9,407.08
  5. Step 5: Solve for x
    x = 9,407.08/80.64
  6. Step 6: Final answer
    x = 116.66

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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.