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Finding the Third Proportional to 258.42 and 390.09

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Solution

The third proportional to 258.42 and 390.09 is: 588.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.42 : 390.09 = 390.09 : x
  2. Step 2: Convert to fraction form
    258.42/390.09 = 390.09/x
  3. Step 3: Cross multiply
    258.42x = 390.09 × 390.09
  4. Step 4: Simplify right side
    258.42x = 152,173.13
  5. Step 5: Solve for x
    x = 152,173.13/258.42
  6. Step 6: Final answer
    x = 588.86

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.