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Finding the Fourth Proportional to 99.12, 136.72 and 66.40

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Solution

The fourth proportional to 99.12, 136.72 and 66.40 is: 91.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.12 : 136.72 = 66.40 : x
  2. Step 2: Convert to fraction form
    99.12/136.72 = 66.40/x
  3. Step 3: Cross multiply
    99.12x = 136.72 × 66.40
  4. Step 4: Simplify right side
    99.12x = 9,078.21
  5. Step 5: Solve for x
    x = 9,078.21/99.12
  6. Step 6: Final answer
    x = 91.59

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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.