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Finding the Fourth Proportional to 120.25, 165.81 and 78.79

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Solution

The fourth proportional to 120.25, 165.81 and 78.79 is: 108.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.25 : 165.81 = 78.79 : x
  2. Step 2: Convert to fraction form
    120.25/165.81 = 78.79/x
  3. Step 3: Cross multiply
    120.25x = 165.81 × 78.79
  4. Step 4: Simplify right side
    120.25x = 13,064.17
  5. Step 5: Solve for x
    x = 13,064.17/120.25
  6. Step 6: Final answer
    x = 108.64

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.