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Finding the Fourth Proportional to 1,398.78, 1,930.35 and 777.78

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Solution

The fourth proportional to 1,398.78, 1,930.35 and 777.78 is: 1,073.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,398.78 : 1,930.35 = 777.78 : x
  2. Step 2: Convert to fraction form
    1,398.78/1,930.35 = 777.78/x
  3. Step 3: Cross multiply
    1,398.78x = 1,930.35 × 777.78
  4. Step 4: Simplify right side
    1,398.78x = 1,501,387.62
  5. Step 5: Solve for x
    x = 1,501,387.62/1,398.78
  6. Step 6: Final answer
    x = 1,073.36

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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.