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Finding the Fourth Proportional to 99.12, 136.78 and 66.42

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Solution

The fourth proportional to 99.12, 136.78 and 66.42 is: 91.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.12 : 136.78 = 66.42 : x
  2. Step 2: Convert to fraction form
    99.12/136.78 = 66.42/x
  3. Step 3: Cross multiply
    99.12x = 136.78 × 66.42
  4. Step 4: Simplify right side
    99.12x = 9,084.93
  5. Step 5: Solve for x
    x = 9,084.93/99.12
  6. Step 6: Final answer
    x = 91.66

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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.