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Finding the Fourth Proportional to 1,278.56, 1,918.31 and 661.87

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Solution

The fourth proportional to 1,278.56, 1,918.31 and 661.87 is: 993.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.56 : 1,918.31 = 661.87 : x
  2. Step 2: Convert to fraction form
    1,278.56/1,918.31 = 661.87/x
  3. Step 3: Cross multiply
    1,278.56x = 1,918.31 × 661.87
  4. Step 4: Simplify right side
    1,278.56x = 1,269,663.73
  5. Step 5: Solve for x
    x = 1,269,663.73/1,278.56
  6. Step 6: Final answer
    x = 993.05

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.