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Finding the Fourth Proportional to 1,206.40, 1,806.90 and 990.40

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Solution

The fourth proportional to 1,206.40, 1,806.90 and 990.40 is: 1,483.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,206.40 : 1,806.90 = 990.40 : x
  2. Step 2: Convert to fraction form
    1,206.40/1,806.90 = 990.40/x
  3. Step 3: Cross multiply
    1,206.40x = 1,806.90 × 990.40
  4. Step 4: Simplify right side
    1,206.40x = 1,789,553.76
  5. Step 5: Solve for x
    x = 1,789,553.76/1,206.40
  6. Step 6: Final answer
    x = 1,483.38

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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.