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Finding the Fourth Proportional to 123.78, 170.59 and 100.38

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Solution

The fourth proportional to 123.78, 170.59 and 100.38 is: 138.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.78 : 170.59 = 100.38 : x
  2. Step 2: Convert to fraction form
    123.78/170.59 = 100.38/x
  3. Step 3: Cross multiply
    123.78x = 170.59 × 100.38
  4. Step 4: Simplify right side
    123.78x = 17,123.82
  5. Step 5: Solve for x
    x = 17,123.82/123.78
  6. Step 6: Final answer
    x = 138.34

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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.