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Finding the Fourth Proportional to 100, 138 and 54

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Solution

The fourth proportional to 100, 138 and 54 is: 74.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    100 : 138 = 54 : x
  2. Step 2: Convert to fraction form
    100/138 = 54/x
  3. Step 3: Cross multiply
    100x = 138 × 54
  4. Step 4: Simplify right side
    100x = 7,452
  5. Step 5: Solve for x
    x = 7,452/100
  6. Step 6: Final answer
    x = 74.52

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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.