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Finding the Fourth Proportional to 2,147.80, 3,221.92 and 687

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Solution

The fourth proportional to 2,147.80, 3,221.92 and 687 is: 1,030.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,147.80 : 3,221.92 = 687 : x
  2. Step 2: Convert to fraction form
    2,147.80/3,221.92 = 687/x
  3. Step 3: Cross multiply
    2,147.80x = 3,221.92 × 687
  4. Step 4: Simplify right side
    2,147.80x = 2,213,459.04
  5. Step 5: Solve for x
    x = 2,213,459.04/2,147.80
  6. Step 6: Final answer
    x = 1,030.57

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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.