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Finding the Fourth Proportional to 100.78, 138.96 and 82.08

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Solution

The fourth proportional to 100.78, 138.96 and 82.08 is: 113.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.78 : 138.96 = 82.08 : x
  2. Step 2: Convert to fraction form
    100.78/138.96 = 82.08/x
  3. Step 3: Cross multiply
    100.78x = 138.96 × 82.08
  4. Step 4: Simplify right side
    100.78x = 11,405.84
  5. Step 5: Solve for x
    x = 11,405.84/100.78
  6. Step 6: Final answer
    x = 113.18

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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.