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Finding the Fourth Proportional to 1,380.05, 2,070.08 and 687.58

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Solution

The fourth proportional to 1,380.05, 2,070.08 and 687.58 is: 1,031.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,380.05 : 2,070.08 = 687.58 : x
  2. Step 2: Convert to fraction form
    1,380.05/2,070.08 = 687.58/x
  3. Step 3: Cross multiply
    1,380.05x = 2,070.08 × 687.58
  4. Step 4: Simplify right side
    1,380.05x = 1,423,339.57
  5. Step 5: Solve for x
    x = 1,423,339.57/1,380.05
  6. Step 6: Final answer
    x = 1,031.37

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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.