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Finding the Third Proportional to 421.25 and 619.75

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Solution

The third proportional to 421.25 and 619.75 is: 911.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.25 : 619.75 = 619.75 : x
  2. Step 2: Convert to fraction form
    421.25/619.75 = 619.75/x
  3. Step 3: Cross multiply
    421.25x = 619.75 × 619.75
  4. Step 4: Simplify right side
    421.25x = 384,090.06
  5. Step 5: Solve for x
    x = 384,090.06/421.25
  6. Step 6: Final answer
    x = 911.79

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Why These Related Problems?

These problems maintain the same ratio (1.47) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.