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Finding the Fourth Proportional to 90.88, 136.08 and 84

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Solution

The fourth proportional to 90.88, 136.08 and 84 is: 125.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.88 : 136.08 = 84 : x
  2. Step 2: Convert to fraction form
    90.88/136.08 = 84/x
  3. Step 3: Cross multiply
    90.88x = 136.08 × 84
  4. Step 4: Simplify right side
    90.88x = 11,430.72
  5. Step 5: Solve for x
    x = 11,430.72/90.88
  6. Step 6: Final answer
    x = 125.78

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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.