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Finding the Third Proportional to 218.53 and 388.13

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Solution

The third proportional to 218.53 and 388.13 is: 689.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    218.53 : 388.13 = 388.13 : x
  2. Step 2: Convert to fraction form
    218.53/388.13 = 388.13/x
  3. Step 3: Cross multiply
    218.53x = 388.13 × 388.13
  4. Step 4: Simplify right side
    218.53x = 150,641.02
  5. Step 5: Solve for x
    x = 150,641.02/218.53
  6. Step 6: Final answer
    x = 689.33

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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.