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Finding the Fourth Proportional to 1,921.40, 2,879.40 and 1,689.20

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Solution

The fourth proportional to 1,921.40, 2,879.40 and 1,689.20 is: 2,531.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,921.40 : 2,879.40 = 1,689.20 : x
  2. Step 2: Convert to fraction form
    1,921.40/2,879.40 = 1,689.20/x
  3. Step 3: Cross multiply
    1,921.40x = 2,879.40 × 1,689.20
  4. Step 4: Simplify right side
    1,921.40x = 4,863,882.48
  5. Step 5: Solve for x
    x = 4,863,882.48/1,921.40
  6. Step 6: Final answer
    x = 2,531.43

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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.