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Finding the Fourth Proportional to 209.40, 288.66 and 143.78

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Solution

The fourth proportional to 209.40, 288.66 and 143.78 is: 198.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.40 : 288.66 = 143.78 : x
  2. Step 2: Convert to fraction form
    209.40/288.66 = 143.78/x
  3. Step 3: Cross multiply
    209.40x = 288.66 × 143.78
  4. Step 4: Simplify right side
    209.40x = 41,503.53
  5. Step 5: Solve for x
    x = 41,503.53/209.40
  6. Step 6: Final answer
    x = 198.20

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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.