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Finding the Fourth Proportional to 91.98, 137.80 and 85.66

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Solution

The fourth proportional to 91.98, 137.80 and 85.66 is: 128.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.98 : 137.80 = 85.66 : x
  2. Step 2: Convert to fraction form
    91.98/137.80 = 85.66/x
  3. Step 3: Cross multiply
    91.98x = 137.80 × 85.66
  4. Step 4: Simplify right side
    91.98x = 11,803.95
  5. Step 5: Solve for x
    x = 11,803.95/91.98
  6. Step 6: Final answer
    x = 128.33

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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.