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Finding the Fourth Proportional to 1,080.78, 1,491.45 and 615

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Solution

The fourth proportional to 1,080.78, 1,491.45 and 615 is: 848.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,080.78 : 1,491.45 = 615 : x
  2. Step 2: Convert to fraction form
    1,080.78/1,491.45 = 615/x
  3. Step 3: Cross multiply
    1,080.78x = 1,491.45 × 615
  4. Step 4: Simplify right side
    1,080.78x = 917,241.75
  5. Step 5: Solve for x
    x = 917,241.75/1,080.78
  6. Step 6: Final answer
    x = 848.68

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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.