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Finding the Fourth Proportional to 1,280.85, 1,919.68 and 664.20

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Solution

The fourth proportional to 1,280.85, 1,919.68 and 664.20 is: 995.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.85 : 1,919.68 = 664.20 : x
  2. Step 2: Convert to fraction form
    1,280.85/1,919.68 = 664.20/x
  3. Step 3: Cross multiply
    1,280.85x = 1,919.68 × 664.20
  4. Step 4: Simplify right side
    1,280.85x = 1,275,051.46
  5. Step 5: Solve for x
    x = 1,275,051.46/1,280.85
  6. Step 6: Final answer
    x = 995.47

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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.