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Finding the Fourth Proportional to 91.16, 136.54 and 78.68

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Solution

The fourth proportional to 91.16, 136.54 and 78.68 is: 117.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.16 : 136.54 = 78.68 : x
  2. Step 2: Convert to fraction form
    91.16/136.54 = 78.68/x
  3. Step 3: Cross multiply
    91.16x = 136.54 × 78.68
  4. Step 4: Simplify right side
    91.16x = 10,742.97
  5. Step 5: Solve for x
    x = 10,742.97/91.16
  6. Step 6: Final answer
    x = 117.85

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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.