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Finding the Fourth Proportional to 100.67, 138.99 and 90.81

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Solution

The fourth proportional to 100.67, 138.99 and 90.81 is: 125.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.67 : 138.99 = 90.81 : x
  2. Step 2: Convert to fraction form
    100.67/138.99 = 90.81/x
  3. Step 3: Cross multiply
    100.67x = 138.99 × 90.81
  4. Step 4: Simplify right side
    100.67x = 12,621.68
  5. Step 5: Solve for x
    x = 12,621.68/100.67
  6. Step 6: Final answer
    x = 125.38

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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.