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Finding the Fourth Proportional to 91.98, 138 and 76.70

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Solution

The fourth proportional to 91.98, 138 and 76.70 is: 115.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.98 : 138 = 76.70 : x
  2. Step 2: Convert to fraction form
    91.98/138 = 76.70/x
  3. Step 3: Cross multiply
    91.98x = 138 × 76.70
  4. Step 4: Simplify right side
    91.98x = 10,584.60
  5. Step 5: Solve for x
    x = 10,584.60/91.98
  6. Step 6: Final answer
    x = 115.08

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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.