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Finding the Third Proportional to 813 and 1,239.75

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Solution

The third proportional to 813 and 1,239.75 is: 1,890.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    813 : 1,239.75 = 1,239.75 : x
  2. Step 2: Convert to fraction form
    813/1,239.75 = 1,239.75/x
  3. Step 3: Cross multiply
    813x = 1,239.75 × 1,239.75
  4. Step 4: Simplify right side
    813x = 1,536,980.06
  5. Step 5: Solve for x
    x = 1,536,980.06/813
  6. Step 6: Final answer
    x = 1,890.50

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Why These Related Problems?

These problems maintain the same ratio (1.52) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.