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Finding the Fourth Proportional to 90.75, 125.15 and 72.12

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Solution

The fourth proportional to 90.75, 125.15 and 72.12 is: 99.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.75 : 125.15 = 72.12 : x
  2. Step 2: Convert to fraction form
    90.75/125.15 = 72.12/x
  3. Step 3: Cross multiply
    90.75x = 125.15 × 72.12
  4. Step 4: Simplify right side
    90.75x = 9,025.46
  5. Step 5: Solve for x
    x = 9,025.46/90.75
  6. Step 6: Final answer
    x = 99.45

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.