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Finding the Third Proportional to 5,128 and 7,840

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Solution

The third proportional to 5,128 and 7,840 is: 11,986.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    5,128 : 7,840 = 7,840 : x
  2. Step 2: Convert to fraction form
    5,128/7,840 = 7,840/x
  3. Step 3: Cross multiply
    5,128x = 7,840 × 7,840
  4. Step 4: Simplify right side
    5,128x = 61,465,600
  5. Step 5: Solve for x
    x = 61,465,600/5,128
  6. Step 6: Final answer
    x = 11,986.27

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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.