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Finding the Fourth Proportional to 1,428.63, 2,142.09 and 687.87

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Solution

The fourth proportional to 1,428.63, 2,142.09 and 687.87 is: 1,031.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,428.63 : 2,142.09 = 687.87 : x
  2. Step 2: Convert to fraction form
    1,428.63/2,142.09 = 687.87/x
  3. Step 3: Cross multiply
    1,428.63x = 2,142.09 × 687.87
  4. Step 4: Simplify right side
    1,428.63x = 1,473,479.45
  5. Step 5: Solve for x
    x = 1,473,479.45/1,428.63
  6. Step 6: Final answer
    x = 1,031.39

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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.