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Finding the Fourth Proportional to 128.79, 177.63 and 82.11

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Solution

The fourth proportional to 128.79, 177.63 and 82.11 is: 113.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.79 : 177.63 = 82.11 : x
  2. Step 2: Convert to fraction form
    128.79/177.63 = 82.11/x
  3. Step 3: Cross multiply
    128.79x = 177.63 × 82.11
  4. Step 4: Simplify right side
    128.79x = 14,585.40
  5. Step 5: Solve for x
    x = 14,585.40/128.79
  6. Step 6: Final answer
    x = 113.25

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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.