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Finding the Fourth Proportional to 1,318.72, 1,978.22 and 394.12

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Solution

The fourth proportional to 1,318.72, 1,978.22 and 394.12 is: 591.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,318.72 : 1,978.22 = 394.12 : x
  2. Step 2: Convert to fraction form
    1,318.72/1,978.22 = 394.12/x
  3. Step 3: Cross multiply
    1,318.72x = 1,978.22 × 394.12
  4. Step 4: Simplify right side
    1,318.72x = 779,649.15
  5. Step 5: Solve for x
    x = 779,649.15/1,318.72
  6. Step 6: Final answer
    x = 591.22

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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.