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Finding the Fourth Proportional to 90.81, 125.30 and 61.70

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Solution

The fourth proportional to 90.81, 125.30 and 61.70 is: 85.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.81 : 125.30 = 61.70 : x
  2. Step 2: Convert to fraction form
    90.81/125.30 = 61.70/x
  3. Step 3: Cross multiply
    90.81x = 125.30 × 61.70
  4. Step 4: Simplify right side
    90.81x = 7,730.08
  5. Step 5: Solve for x
    x = 7,730.08/90.81
  6. Step 6: Final answer
    x = 85.12

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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.