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Finding the Fourth Proportional to 989.80, 1,484.70 and 809.80

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Solution

The fourth proportional to 989.80, 1,484.70 and 809.80 is: 1,214.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.80 : 1,484.70 = 809.80 : x
  2. Step 2: Convert to fraction form
    989.80/1,484.70 = 809.80/x
  3. Step 3: Cross multiply
    989.80x = 1,484.70 × 809.80
  4. Step 4: Simplify right side
    989.80x = 1,202,310.06
  5. Step 5: Solve for x
    x = 1,202,310.06/989.80
  6. Step 6: Final answer
    x = 1,214.70

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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.