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Finding the Fourth Proportional to 980.39, 1,469.38 and 721.50

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Solution

The fourth proportional to 980.39, 1,469.38 and 721.50 is: 1,081.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    980.39 : 1,469.38 = 721.50 : x
  2. Step 2: Convert to fraction form
    980.39/1,469.38 = 721.50/x
  3. Step 3: Cross multiply
    980.39x = 1,469.38 × 721.50
  4. Step 4: Simplify right side
    980.39x = 1,060,157.67
  5. Step 5: Solve for x
    x = 1,060,157.67/980.39
  6. Step 6: Final answer
    x = 1,081.36

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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.