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Finding the Third Proportional to 1,280 and 1,987.75

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Solution

The third proportional to 1,280 and 1,987.75 is: 3,086.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280 : 1,987.75 = 1,987.75 : x
  2. Step 2: Convert to fraction form
    1,280/1,987.75 = 1,987.75/x
  3. Step 3: Cross multiply
    1,280x = 1,987.75 × 1,987.75
  4. Step 4: Simplify right side
    1,280x = 3,951,150.06
  5. Step 5: Solve for x
    x = 3,951,150.06/1,280
  6. Step 6: Final answer
    x = 3,086.84

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Why These Related Problems?

These problems maintain the same ratio (1.55) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.