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Finding the Fourth Proportional to 212.80, 318.89 and 121.31

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Solution

The fourth proportional to 212.80, 318.89 and 121.31 is: 181.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.80 : 318.89 = 121.31 : x
  2. Step 2: Convert to fraction form
    212.80/318.89 = 121.31/x
  3. Step 3: Cross multiply
    212.80x = 318.89 × 121.31
  4. Step 4: Simplify right side
    212.80x = 38,683.25
  5. Step 5: Solve for x
    x = 38,683.25/212.80
  6. Step 6: Final answer
    x = 181.78

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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.