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Finding the Fourth Proportional to 1,318.97, 1,978.65 and 394.43

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Solution

The fourth proportional to 1,318.97, 1,978.65 and 394.43 is: 591.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,318.97 : 1,978.65 = 394.43 : x
  2. Step 2: Convert to fraction form
    1,318.97/1,978.65 = 394.43/x
  3. Step 3: Cross multiply
    1,318.97x = 1,978.65 × 394.43
  4. Step 4: Simplify right side
    1,318.97x = 780,429.03
  5. Step 5: Solve for x
    x = 780,429.03/1,318.97
  6. Step 6: Final answer
    x = 591.69

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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.