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Finding the Third Proportional to 421.45 and 489.80

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Solution

The third proportional to 421.45 and 489.80 is: 569.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.45 : 489.80 = 489.80 : x
  2. Step 2: Convert to fraction form
    421.45/489.80 = 489.80/x
  3. Step 3: Cross multiply
    421.45x = 489.80 × 489.80
  4. Step 4: Simplify right side
    421.45x = 239,900.98
  5. Step 5: Solve for x
    x = 239,900.98/421.45
  6. Step 6: Final answer
    x = 569.22

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Why These Related Problems?

These problems maintain the same ratio (1.16) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.