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Finding the Fourth Proportional to 305.65, 421.90 and 209.84

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Solution

The fourth proportional to 305.65, 421.90 and 209.84 is: 289.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    305.65 : 421.90 = 209.84 : x
  2. Step 2: Convert to fraction form
    305.65/421.90 = 209.84/x
  3. Step 3: Cross multiply
    305.65x = 421.90 × 209.84
  4. Step 4: Simplify right side
    305.65x = 88,530.94
  5. Step 5: Solve for x
    x = 88,530.94/305.65
  6. Step 6: Final answer
    x = 289.65

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.