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Finding the Fourth Proportional to 90.65, 135.24 and 77.66

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Solution

The fourth proportional to 90.65, 135.24 and 77.66 is: 115.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.65 : 135.24 = 77.66 : x
  2. Step 2: Convert to fraction form
    90.65/135.24 = 77.66/x
  3. Step 3: Cross multiply
    90.65x = 135.24 × 77.66
  4. Step 4: Simplify right side
    90.65x = 10,502.06
  5. Step 5: Solve for x
    x = 10,502.06/90.65
  6. Step 6: Final answer
    x = 115.86

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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.