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Finding the Third Proportional to 639.56 and 990.56

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Solution

The third proportional to 639.56 and 990.56 is: 1,534.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.56 : 990.56 = 990.56 : x
  2. Step 2: Convert to fraction form
    639.56/990.56 = 990.56/x
  3. Step 3: Cross multiply
    639.56x = 990.56 × 990.56
  4. Step 4: Simplify right side
    639.56x = 981,214.07
  5. Step 5: Solve for x
    x = 981,214.07/639.56
  6. Step 6: Final answer
    x = 1,534.20

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Why These Related Problems?

These problems maintain the same ratio (1.55) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.