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Finding the Fourth Proportional to 1,318.65, 1,978.01 and 394.20

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Solution

The fourth proportional to 1,318.65, 1,978.01 and 394.20 is: 591.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,318.65 : 1,978.01 = 394.20 : x
  2. Step 2: Convert to fraction form
    1,318.65/1,978.01 = 394.20/x
  3. Step 3: Cross multiply
    1,318.65x = 1,978.01 × 394.20
  4. Step 4: Simplify right side
    1,318.65x = 779,731.54
  5. Step 5: Solve for x
    x = 779,731.54/1,318.65
  6. Step 6: Final answer
    x = 591.31

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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.