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Finding the Fourth Proportional to 998.78, 1,378.31 and 556.68

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Solution

The fourth proportional to 998.78, 1,378.31 and 556.68 is: 768.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    998.78 : 1,378.31 = 556.68 : x
  2. Step 2: Convert to fraction form
    998.78/1,378.31 = 556.68/x
  3. Step 3: Cross multiply
    998.78x = 1,378.31 × 556.68
  4. Step 4: Simplify right side
    998.78x = 767,270.72
  5. Step 5: Solve for x
    x = 767,270.72/998.78
  6. Step 6: Final answer
    x = 768.21

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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.