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Finding the Fourth Proportional to 2,139, 3,208.50 and 771

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Solution

The fourth proportional to 2,139, 3,208.50 and 771 is: 1,156.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    2,139 : 3,208.50 = 771 : x
  2. Step 2: Convert to fraction form
    2,139/3,208.50 = 771/x
  3. Step 3: Cross multiply
    2,139x = 3,208.50 × 771
  4. Step 4: Simplify right side
    2,139x = 2,473,753.50
  5. Step 5: Solve for x
    x = 2,473,753.50/2,139
  6. Step 6: Final answer
    x = 1,156.50

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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.