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Finding the Fourth Proportional to 1,319.46, 1,978.85 and 394.78

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Solution

The fourth proportional to 1,319.46, 1,978.85 and 394.78 is: 592.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,319.46 : 1,978.85 = 394.78 : x
  2. Step 2: Convert to fraction form
    1,319.46/1,978.85 = 394.78/x
  3. Step 3: Cross multiply
    1,319.46x = 1,978.85 × 394.78
  4. Step 4: Simplify right side
    1,319.46x = 781,210.40
  5. Step 5: Solve for x
    x = 781,210.40/1,319.46
  6. Step 6: Final answer
    x = 592.07

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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.