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Finding the Fourth Proportional to 138.12, 190.64 and 79.90

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Solution

The fourth proportional to 138.12, 190.64 and 79.90 is: 110.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.12 : 190.64 = 79.90 : x
  2. Step 2: Convert to fraction form
    138.12/190.64 = 79.90/x
  3. Step 3: Cross multiply
    138.12x = 190.64 × 79.90
  4. Step 4: Simplify right side
    138.12x = 15,232.14
  5. Step 5: Solve for x
    x = 15,232.14/138.12
  6. Step 6: Final answer
    x = 110.28

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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.