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Finding the Third Proportional to 138.50 and 315.50

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Solution

The third proportional to 138.50 and 315.50 is: 718.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.50 : 315.50 = 315.50 : x
  2. Step 2: Convert to fraction form
    138.50/315.50 = 315.50/x
  3. Step 3: Cross multiply
    138.50x = 315.50 × 315.50
  4. Step 4: Simplify right side
    138.50x = 99,540.25
  5. Step 5: Solve for x
    x = 99,540.25/138.50
  6. Step 6: Final answer
    x = 718.70

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Why These Related Problems?

These problems maintain the same ratio (2.28) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.