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Finding the Fourth Proportional to 90.99, 135.72 and 86.94

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Solution

The fourth proportional to 90.99, 135.72 and 86.94 is: 129.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.99 : 135.72 = 86.94 : x
  2. Step 2: Convert to fraction form
    90.99/135.72 = 86.94/x
  3. Step 3: Cross multiply
    90.99x = 135.72 × 86.94
  4. Step 4: Simplify right side
    90.99x = 11,799.50
  5. Step 5: Solve for x
    x = 11,799.50/90.99
  6. Step 6: Final answer
    x = 129.68

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.