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Finding the Third Proportional to 74.78 and 109.21

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Solution

The third proportional to 74.78 and 109.21 is: 159.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    74.78 : 109.21 = 109.21 : x
  2. Step 2: Convert to fraction form
    74.78/109.21 = 109.21/x
  3. Step 3: Cross multiply
    74.78x = 109.21 × 109.21
  4. Step 4: Simplify right side
    74.78x = 11,927.46
  5. Step 5: Solve for x
    x = 11,927.46/74.78
  6. Step 6: Final answer
    x = 159.51

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Why These Related Problems?

These problems maintain the same ratio (1.46) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.