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Finding the Fourth Proportional to 208, 312.13 and 99.80

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Solution

The fourth proportional to 208, 312.13 and 99.80 is: 149.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    208 : 312.13 = 99.80 : x
  2. Step 2: Convert to fraction form
    208/312.13 = 99.80/x
  3. Step 3: Cross multiply
    208x = 312.13 × 99.80
  4. Step 4: Simplify right side
    208x = 31,150.57
  5. Step 5: Solve for x
    x = 31,150.57/208
  6. Step 6: Final answer
    x = 149.76

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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.