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Finding the Fourth Proportional to 155.78, 215 and 100.56

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Solution

The fourth proportional to 155.78, 215 and 100.56 is: 138.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    155.78 : 215 = 100.56 : x
  2. Step 2: Convert to fraction form
    155.78/215 = 100.56/x
  3. Step 3: Cross multiply
    155.78x = 215 × 100.56
  4. Step 4: Simplify right side
    155.78x = 21,620.40
  5. Step 5: Solve for x
    x = 21,620.40/155.78
  6. Step 6: Final answer
    x = 138.79

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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.