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Finding the Fourth Proportional to 128.74, 192.56 and 87.70

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Solution

The fourth proportional to 128.74, 192.56 and 87.70 is: 131.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.74 : 192.56 = 87.70 : x
  2. Step 2: Convert to fraction form
    128.74/192.56 = 87.70/x
  3. Step 3: Cross multiply
    128.74x = 192.56 × 87.70
  4. Step 4: Simplify right side
    128.74x = 16,887.51
  5. Step 5: Solve for x
    x = 16,887.51/128.74
  6. Step 6: Final answer
    x = 131.18

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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.