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Finding the Fourth Proportional to 208.12, 311.94 and 99.78

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Solution

The fourth proportional to 208.12, 311.94 and 99.78 is: 149.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.12 : 311.94 = 99.78 : x
  2. Step 2: Convert to fraction form
    208.12/311.94 = 99.78/x
  3. Step 3: Cross multiply
    208.12x = 311.94 × 99.78
  4. Step 4: Simplify right side
    208.12x = 31,125.37
  5. Step 5: Solve for x
    x = 31,125.37/208.12
  6. Step 6: Final answer
    x = 149.56

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.