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Finding the Third Proportional to 780.75 and 1,638

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Solution

The third proportional to 780.75 and 1,638 is: 3,436.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    780.75 : 1,638 = 1,638 : x
  2. Step 2: Convert to fraction form
    780.75/1,638 = 1,638/x
  3. Step 3: Cross multiply
    780.75x = 1,638 × 1,638
  4. Step 4: Simplify right side
    780.75x = 2,683,044
  5. Step 5: Solve for x
    x = 2,683,044/780.75
  6. Step 6: Final answer
    x = 3,436.50

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Why These Related Problems?

These problems maintain the same ratio (2.10) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.