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Finding the Fourth Proportional to 91.90, 137.64 and 90.05

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Solution

The fourth proportional to 91.90, 137.64 and 90.05 is: 134.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.90 : 137.64 = 90.05 : x
  2. Step 2: Convert to fraction form
    91.90/137.64 = 90.05/x
  3. Step 3: Cross multiply
    91.90x = 137.64 × 90.05
  4. Step 4: Simplify right side
    91.90x = 12,394.48
  5. Step 5: Solve for x
    x = 12,394.48/91.90
  6. Step 6: Final answer
    x = 134.88

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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.