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Finding the Fourth Proportional to 90, 123.81 and 84.96

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Solution

The fourth proportional to 90, 123.81 and 84.96 is: 116.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    90 : 123.81 = 84.96 : x
  2. Step 2: Convert to fraction form
    90/123.81 = 84.96/x
  3. Step 3: Cross multiply
    90x = 123.81 × 84.96
  4. Step 4: Simplify right side
    90x = 10,518.90
  5. Step 5: Solve for x
    x = 10,518.90/90
  6. Step 6: Final answer
    x = 116.88

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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.