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Finding the Fourth Proportional to 99.78, 149.70 and 54.12

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Solution

The fourth proportional to 99.78, 149.70 and 54.12 is: 81.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.78 : 149.70 = 54.12 : x
  2. Step 2: Convert to fraction form
    99.78/149.70 = 54.12/x
  3. Step 3: Cross multiply
    99.78x = 149.70 × 54.12
  4. Step 4: Simplify right side
    99.78x = 8,101.38
  5. Step 5: Solve for x
    x = 8,101.38/99.78
  6. Step 6: Final answer
    x = 81.19

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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.