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Finding the Fourth Proportional to 90.80, 136.28 and 66.88

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Solution

The fourth proportional to 90.80, 136.28 and 66.88 is: 100.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.80 : 136.28 = 66.88 : x
  2. Step 2: Convert to fraction form
    90.80/136.28 = 66.88/x
  3. Step 3: Cross multiply
    90.80x = 136.28 × 66.88
  4. Step 4: Simplify right side
    90.80x = 9,114.41
  5. Step 5: Solve for x
    x = 9,114.41/90.80
  6. Step 6: Final answer
    x = 100.38

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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.