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Finding the Fourth Proportional to 980.86, 1,471.31 and 387.86

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Solution

The fourth proportional to 980.86, 1,471.31 and 387.86 is: 581.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    980.86 : 1,471.31 = 387.86 : x
  2. Step 2: Convert to fraction form
    980.86/1,471.31 = 387.86/x
  3. Step 3: Cross multiply
    980.86x = 1,471.31 × 387.86
  4. Step 4: Simplify right side
    980.86x = 570,656.64
  5. Step 5: Solve for x
    x = 570,656.64/980.86
  6. Step 6: Final answer
    x = 581.79

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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.