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Finding the Fourth Proportional to 92.78, 128.12 and 76.53

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Solution

The fourth proportional to 92.78, 128.12 and 76.53 is: 105.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    92.78 : 128.12 = 76.53 : x
  2. Step 2: Convert to fraction form
    92.78/128.12 = 76.53/x
  3. Step 3: Cross multiply
    92.78x = 128.12 × 76.53
  4. Step 4: Simplify right side
    92.78x = 9,804.64
  5. Step 5: Solve for x
    x = 9,804.64/92.78
  6. Step 6: Final answer
    x = 105.68

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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.