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Finding the Third Proportional to 685 and 1,218.50

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Solution

The third proportional to 685 and 1,218.50 is: 2,167.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    685 : 1,218.50 = 1,218.50 : x
  2. Step 2: Convert to fraction form
    685/1,218.50 = 1,218.50/x
  3. Step 3: Cross multiply
    685x = 1,218.50 × 1,218.50
  4. Step 4: Simplify right side
    685x = 1,484,742.25
  5. Step 5: Solve for x
    x = 1,484,742.25/685
  6. Step 6: Final answer
    x = 2,167.51

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Why These Related Problems?

These problems maintain the same ratio (1.78) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.