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Finding the Fourth Proportional to 128, 190.72 and 126.72

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Solution

The fourth proportional to 128, 190.72 and 126.72 is: 188.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    128 : 190.72 = 126.72 : x
  2. Step 2: Convert to fraction form
    128/190.72 = 126.72/x
  3. Step 3: Cross multiply
    128x = 190.72 × 126.72
  4. Step 4: Simplify right side
    128x = 24,168.04
  5. Step 5: Solve for x
    x = 24,168.04/128
  6. Step 6: Final answer
    x = 188.81

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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.