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Finding the Fourth Proportional to 1,287.60, 1,930.20 and 1,009.80

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Solution

The fourth proportional to 1,287.60, 1,930.20 and 1,009.80 is: 1,513.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.60 : 1,930.20 = 1,009.80 : x
  2. Step 2: Convert to fraction form
    1,287.60/1,930.20 = 1,009.80/x
  3. Step 3: Cross multiply
    1,287.60x = 1,930.20 × 1,009.80
  4. Step 4: Simplify right side
    1,287.60x = 1,949,115.96
  5. Step 5: Solve for x
    x = 1,949,115.96/1,287.60
  6. Step 6: Final answer
    x = 1,513.76

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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.