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Finding the Fourth Proportional to 128.95, 177.89 and 85.32

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Solution

The fourth proportional to 128.95, 177.89 and 85.32 is: 117.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.95 : 177.89 = 85.32 : x
  2. Step 2: Convert to fraction form
    128.95/177.89 = 85.32/x
  3. Step 3: Cross multiply
    128.95x = 177.89 × 85.32
  4. Step 4: Simplify right side
    128.95x = 15,177.15
  5. Step 5: Solve for x
    x = 15,177.15/128.95
  6. Step 6: Final answer
    x = 117.70

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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.