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Finding the Fourth Proportional to 80.78, 111.40 and 65.14

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Solution

The fourth proportional to 80.78, 111.40 and 65.14 is: 89.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.78 : 111.40 = 65.14 : x
  2. Step 2: Convert to fraction form
    80.78/111.40 = 65.14/x
  3. Step 3: Cross multiply
    80.78x = 111.40 × 65.14
  4. Step 4: Simplify right side
    80.78x = 7,256.15
  5. Step 5: Solve for x
    x = 7,256.15/80.78
  6. Step 6: Final answer
    x = 89.83

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.