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Finding the Fourth Proportional to 1,986.48, 2,979.84 and 687.76

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Solution

The fourth proportional to 1,986.48, 2,979.84 and 687.76 is: 1,031.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,986.48 : 2,979.84 = 687.76 : x
  2. Step 2: Convert to fraction form
    1,986.48/2,979.84 = 687.76/x
  3. Step 3: Cross multiply
    1,986.48x = 2,979.84 × 687.76
  4. Step 4: Simplify right side
    1,986.48x = 2,049,414.76
  5. Step 5: Solve for x
    x = 2,049,414.76/1,986.48
  6. Step 6: Final answer
    x = 1,031.68

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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.