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Finding the Fourth Proportional to 128.25, 192.38 and 42.75

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Solution

The fourth proportional to 128.25, 192.38 and 42.75 is: 64.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.25 : 192.38 = 42.75 : x
  2. Step 2: Convert to fraction form
    128.25/192.38 = 42.75/x
  3. Step 3: Cross multiply
    128.25x = 192.38 × 42.75
  4. Step 4: Simplify right side
    128.25x = 8,224.03
  5. Step 5: Solve for x
    x = 8,224.03/128.25
  6. Step 6: Final answer
    x = 64.13

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.