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Finding the Fourth Proportional to 91.30, 137.48 and 85.90

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Solution

The fourth proportional to 91.30, 137.48 and 85.90 is: 129.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.30 : 137.48 = 85.90 : x
  2. Step 2: Convert to fraction form
    91.30/137.48 = 85.90/x
  3. Step 3: Cross multiply
    91.30x = 137.48 × 85.90
  4. Step 4: Simplify right side
    91.30x = 11,809.53
  5. Step 5: Solve for x
    x = 11,809.53/91.30
  6. Step 6: Final answer
    x = 129.35

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.