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Finding the Fourth Proportional to 1,290.40, 1,940.40 and 1,079.20

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Solution

The fourth proportional to 1,290.40, 1,940.40 and 1,079.20 is: 1,622.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.40 : 1,940.40 = 1,079.20 : x
  2. Step 2: Convert to fraction form
    1,290.40/1,940.40 = 1,079.20/x
  3. Step 3: Cross multiply
    1,290.40x = 1,940.40 × 1,079.20
  4. Step 4: Simplify right side
    1,290.40x = 2,094,079.68
  5. Step 5: Solve for x
    x = 2,094,079.68/1,290.40
  6. Step 6: Final answer
    x = 1,622.81

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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.