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Finding the Fourth Proportional to 1,920.79, 2,879.36 and 687.56

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Solution

The fourth proportional to 1,920.79, 2,879.36 and 687.56 is: 1,030.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,920.79 : 2,879.36 = 687.56 : x
  2. Step 2: Convert to fraction form
    1,920.79/2,879.36 = 687.56/x
  3. Step 3: Cross multiply
    1,920.79x = 2,879.36 × 687.56
  4. Step 4: Simplify right side
    1,920.79x = 1,979,731.77
  5. Step 5: Solve for x
    x = 1,979,731.77/1,920.79
  6. Step 6: Final answer
    x = 1,030.69

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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.