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Finding the Fourth Proportional to 128.16, 176.79 and 100.49

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Solution

The fourth proportional to 128.16, 176.79 and 100.49 is: 138.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.16 : 176.79 = 100.49 : x
  2. Step 2: Convert to fraction form
    128.16/176.79 = 100.49/x
  3. Step 3: Cross multiply
    128.16x = 176.79 × 100.49
  4. Step 4: Simplify right side
    128.16x = 17,765.63
  5. Step 5: Solve for x
    x = 17,765.63/128.16
  6. Step 6: Final answer
    x = 138.62

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.