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Finding the Fourth Proportional to 138.31, 190.86 and 79.28

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Solution

The fourth proportional to 138.31, 190.86 and 79.28 is: 109.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.31 : 190.86 = 79.28 : x
  2. Step 2: Convert to fraction form
    138.31/190.86 = 79.28/x
  3. Step 3: Cross multiply
    138.31x = 190.86 × 79.28
  4. Step 4: Simplify right side
    138.31x = 15,130.84
  5. Step 5: Solve for x
    x = 15,130.84/138.31
  6. Step 6: Final answer
    x = 109.40

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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.