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Finding the Fourth Proportional to 91.07, 136.68 and 76.78

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Solution

The fourth proportional to 91.07, 136.68 and 76.78 is: 115.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.07 : 136.68 = 76.78 : x
  2. Step 2: Convert to fraction form
    91.07/136.68 = 76.78/x
  3. Step 3: Cross multiply
    91.07x = 136.68 × 76.78
  4. Step 4: Simplify right side
    91.07x = 10,494.29
  5. Step 5: Solve for x
    x = 10,494.29/91.07
  6. Step 6: Final answer
    x = 115.23

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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.