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Finding the Third Proportional to 309.75 and 687.88

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Solution

The third proportional to 309.75 and 687.88 is: 1,527.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    309.75 : 687.88 = 687.88 : x
  2. Step 2: Convert to fraction form
    309.75/687.88 = 687.88/x
  3. Step 3: Cross multiply
    309.75x = 687.88 × 687.88
  4. Step 4: Simplify right side
    309.75x = 473,172.02
  5. Step 5: Solve for x
    x = 473,172.02/309.75
  6. Step 6: Final answer
    x = 1,527.59

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Why These Related Problems?

These problems maintain the same ratio (2.22) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.