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Finding the Fourth Proportional to 128.82, 177.62 and 85.08

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Solution

The fourth proportional to 128.82, 177.62 and 85.08 is: 117.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.82 : 177.62 = 85.08 : x
  2. Step 2: Convert to fraction form
    128.82/177.62 = 85.08/x
  3. Step 3: Cross multiply
    128.82x = 177.62 × 85.08
  4. Step 4: Simplify right side
    128.82x = 15,111.48
  5. Step 5: Solve for x
    x = 15,111.48/128.82
  6. Step 6: Final answer
    x = 117.31

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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.