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Finding the Fourth Proportional to 118.36, 177.42 and 85.78

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Solution

The fourth proportional to 118.36, 177.42 and 85.78 is: 128.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    118.36 : 177.42 = 85.78 : x
  2. Step 2: Convert to fraction form
    118.36/177.42 = 85.78/x
  3. Step 3: Cross multiply
    118.36x = 177.42 × 85.78
  4. Step 4: Simplify right side
    118.36x = 15,219.02
  5. Step 5: Solve for x
    x = 15,219.02/118.36
  6. Step 6: Final answer
    x = 128.58

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.