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Finding the Fourth Proportional to 128.19, 176.90 and 91.41

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Solution

The fourth proportional to 128.19, 176.90 and 91.41 is: 126.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.19 : 176.90 = 91.41 : x
  2. Step 2: Convert to fraction form
    128.19/176.90 = 91.41/x
  3. Step 3: Cross multiply
    128.19x = 176.90 × 91.41
  4. Step 4: Simplify right side
    128.19x = 16,170.43
  5. Step 5: Solve for x
    x = 16,170.43/128.19
  6. Step 6: Final answer
    x = 126.14

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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.