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Finding the Fourth Proportional to 1,987.29, 2,979.10 and 687.85

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Solution

The fourth proportional to 1,987.29, 2,979.10 and 687.85 is: 1,031.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,987.29 : 2,979.10 = 687.85 : x
  2. Step 2: Convert to fraction form
    1,987.29/2,979.10 = 687.85/x
  3. Step 3: Cross multiply
    1,987.29x = 2,979.10 × 687.85
  4. Step 4: Simplify right side
    1,987.29x = 2,049,164.77
  5. Step 5: Solve for x
    x = 2,049,164.77/1,987.29
  6. Step 6: Final answer
    x = 1,031.14

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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.