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Finding the Fourth Proportional to 90.21, 134.31 and 89.70

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Solution

The fourth proportional to 90.21, 134.31 and 89.70 is: 133.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.21 : 134.31 = 89.70 : x
  2. Step 2: Convert to fraction form
    90.21/134.31 = 89.70/x
  3. Step 3: Cross multiply
    90.21x = 134.31 × 89.70
  4. Step 4: Simplify right side
    90.21x = 12,047.61
  5. Step 5: Solve for x
    x = 12,047.61/90.21
  6. Step 6: Final answer
    x = 133.55

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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.