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Finding the Fourth Proportional to 91.15, 125.78 and 66.60

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Solution

The fourth proportional to 91.15, 125.78 and 66.60 is: 91.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.15 : 125.78 = 66.60 : x
  2. Step 2: Convert to fraction form
    91.15/125.78 = 66.60/x
  3. Step 3: Cross multiply
    91.15x = 125.78 × 66.60
  4. Step 4: Simplify right side
    91.15x = 8,376.62
  5. Step 5: Solve for x
    x = 8,376.62/91.15
  6. Step 6: Final answer
    x = 91.90

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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.