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Finding the Third Proportional to 421.88 and 646.31

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Solution

The third proportional to 421.88 and 646.31 is: 990.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.88 : 646.31 = 646.31 : x
  2. Step 2: Convert to fraction form
    421.88/646.31 = 646.31/x
  3. Step 3: Cross multiply
    421.88x = 646.31 × 646.31
  4. Step 4: Simplify right side
    421.88x = 417,719.85
  5. Step 5: Solve for x
    x = 417,719.85/421.88
  6. Step 6: Final answer
    x = 990.15

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Why These Related Problems?

These problems maintain the same ratio (1.53) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.