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Finding the Fourth Proportional to 143.89, 198.56 and 78.39

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Solution

The fourth proportional to 143.89, 198.56 and 78.39 is: 108.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    143.89 : 198.56 = 78.39 : x
  2. Step 2: Convert to fraction form
    143.89/198.56 = 78.39/x
  3. Step 3: Cross multiply
    143.89x = 198.56 × 78.39
  4. Step 4: Simplify right side
    143.89x = 15,565.12
  5. Step 5: Solve for x
    x = 15,565.12/143.89
  6. Step 6: Final answer
    x = 108.17

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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.