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Finding the Fourth Proportional to 90.60, 125.70 and 83.40

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Solution

The fourth proportional to 90.60, 125.70 and 83.40 is: 115.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.60 : 125.70 = 83.40 : x
  2. Step 2: Convert to fraction form
    90.60/125.70 = 83.40/x
  3. Step 3: Cross multiply
    90.60x = 125.70 × 83.40
  4. Step 4: Simplify right side
    90.60x = 10,483.38
  5. Step 5: Solve for x
    x = 10,483.38/90.60
  6. Step 6: Final answer
    x = 115.71

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.