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Finding the Fourth Proportional to 208.20, 312.30 and 121.80

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Solution

The fourth proportional to 208.20, 312.30 and 121.80 is: 182.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.20 : 312.30 = 121.80 : x
  2. Step 2: Convert to fraction form
    208.20/312.30 = 121.80/x
  3. Step 3: Cross multiply
    208.20x = 312.30 × 121.80
  4. Step 4: Simplify right side
    208.20x = 38,038.14
  5. Step 5: Solve for x
    x = 38,038.14/208.20
  6. Step 6: Final answer
    x = 182.70

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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.