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Finding the Fourth Proportional to 1,320.40, 1,985.40 and 1,109.20

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Solution

The fourth proportional to 1,320.40, 1,985.40 and 1,109.20 is: 1,667.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,320.40 : 1,985.40 = 1,109.20 : x
  2. Step 2: Convert to fraction form
    1,320.40/1,985.40 = 1,109.20/x
  3. Step 3: Cross multiply
    1,320.40x = 1,985.40 × 1,109.20
  4. Step 4: Simplify right side
    1,320.40x = 2,202,205.68
  5. Step 5: Solve for x
    x = 2,202,205.68/1,320.40
  6. Step 6: Final answer
    x = 1,667.83

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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.