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Finding the Fourth Proportional to 128.21, 191.09 and 128.00

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Solution

The fourth proportional to 128.21, 191.09 and 128.00 is: 190.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.21 : 191.09 = 128.00 : x
  2. Step 2: Convert to fraction form
    128.21/191.09 = 128.00/x
  3. Step 3: Cross multiply
    128.21x = 191.09 × 128.00
  4. Step 4: Simplify right side
    128.21x = 24,457.92
  5. Step 5: Solve for x
    x = 24,457.92/128.21
  6. Step 6: Final answer
    x = 190.77

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.