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Finding the Fourth Proportional to 128.51, 177.38 and 81.96

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Solution

The fourth proportional to 128.51, 177.38 and 81.96 is: 113.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.51 : 177.38 = 81.96 : x
  2. Step 2: Convert to fraction form
    128.51/177.38 = 81.96/x
  3. Step 3: Cross multiply
    128.51x = 177.38 × 81.96
  4. Step 4: Simplify right side
    128.51x = 14,538.06
  5. Step 5: Solve for x
    x = 14,538.06/128.51
  6. Step 6: Final answer
    x = 113.13

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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.