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Finding the Fourth Proportional to 90.75, 124.81 and 72.11

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Solution

The fourth proportional to 90.75, 124.81 and 72.11 is: 99.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.75 : 124.81 = 72.11 : x
  2. Step 2: Convert to fraction form
    90.75/124.81 = 72.11/x
  3. Step 3: Cross multiply
    90.75x = 124.81 × 72.11
  4. Step 4: Simplify right side
    90.75x = 8,999.69
  5. Step 5: Solve for x
    x = 8,999.69/90.75
  6. Step 6: Final answer
    x = 99.17

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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.