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Finding the Third Proportional to 258.50 and 405.50

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Solution

The third proportional to 258.50 and 405.50 is: 636.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.50 : 405.50 = 405.50 : x
  2. Step 2: Convert to fraction form
    258.50/405.50 = 405.50/x
  3. Step 3: Cross multiply
    258.50x = 405.50 × 405.50
  4. Step 4: Simplify right side
    258.50x = 164,430.25
  5. Step 5: Solve for x
    x = 164,430.25/258.50
  6. Step 6: Final answer
    x = 636.09

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Why These Related Problems?

These problems maintain the same ratio (1.57) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.