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Finding the Fourth Proportional to 207.90, 311.94 and 99.78

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Solution

The fourth proportional to 207.90, 311.94 and 99.78 is: 149.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    207.90 : 311.94 = 99.78 : x
  2. Step 2: Convert to fraction form
    207.90/311.94 = 99.78/x
  3. Step 3: Cross multiply
    207.90x = 311.94 × 99.78
  4. Step 4: Simplify right side
    207.90x = 31,125.37
  5. Step 5: Solve for x
    x = 31,125.37/207.90
  6. Step 6: Final answer
    x = 149.71

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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.