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Finding the Fourth Proportional to 1,319.24, 1,978.90 and 394.80

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Solution

The fourth proportional to 1,319.24, 1,978.90 and 394.80 is: 592.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,319.24 : 1,978.90 = 394.80 : x
  2. Step 2: Convert to fraction form
    1,319.24/1,978.90 = 394.80/x
  3. Step 3: Cross multiply
    1,319.24x = 1,978.90 × 394.80
  4. Step 4: Simplify right side
    1,319.24x = 781,269.72
  5. Step 5: Solve for x
    x = 781,269.72/1,319.24
  6. Step 6: Final answer
    x = 592.21

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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.