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Finding the Third Proportional to 121.25 and 217.50

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Solution

The third proportional to 121.25 and 217.50 is: 390.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    121.25 : 217.50 = 217.50 : x
  2. Step 2: Convert to fraction form
    121.25/217.50 = 217.50/x
  3. Step 3: Cross multiply
    121.25x = 217.50 × 217.50
  4. Step 4: Simplify right side
    121.25x = 47,306.25
  5. Step 5: Solve for x
    x = 47,306.25/121.25
  6. Step 6: Final answer
    x = 390.15

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Why These Related Problems?

These problems maintain the same ratio (1.79) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.