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Finding the Fourth Proportional to 120.42, 165.78 and 115.56

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Solution

The fourth proportional to 120.42, 165.78 and 115.56 is: 159.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.42 : 165.78 = 115.56 : x
  2. Step 2: Convert to fraction form
    120.42/165.78 = 115.56/x
  3. Step 3: Cross multiply
    120.42x = 165.78 × 115.56
  4. Step 4: Simplify right side
    120.42x = 19,157.54
  5. Step 5: Solve for x
    x = 19,157.54/120.42
  6. Step 6: Final answer
    x = 159.09

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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.