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Finding the Fourth Proportional to 128.57, 192.74 and 70.72

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Solution

The fourth proportional to 128.57, 192.74 and 70.72 is: 106.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.57 : 192.74 = 70.72 : x
  2. Step 2: Convert to fraction form
    128.57/192.74 = 70.72/x
  3. Step 3: Cross multiply
    128.57x = 192.74 × 70.72
  4. Step 4: Simplify right side
    128.57x = 13,629.74
  5. Step 5: Solve for x
    x = 13,629.74/128.57
  6. Step 6: Final answer
    x = 106.01

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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.