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Finding the Fourth Proportional to 208.55, 312.80 and 121.61

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Solution

The fourth proportional to 208.55, 312.80 and 121.61 is: 182.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    208.55 : 312.80 = 121.61 : x
  2. Step 2: Convert to fraction form
    208.55/312.80 = 121.61/x
  3. Step 3: Cross multiply
    208.55x = 312.80 × 121.61
  4. Step 4: Simplify right side
    208.55x = 38,039.78
  5. Step 5: Solve for x
    x = 38,039.78/208.55
  6. Step 6: Final answer
    x = 182.40

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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.