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Finding the Fourth Proportional to 209.28, 313.89 and 128.64

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Solution

The fourth proportional to 209.28, 313.89 and 128.64 is: 192.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.28 : 313.89 = 128.64 : x
  2. Step 2: Convert to fraction form
    209.28/313.89 = 128.64/x
  3. Step 3: Cross multiply
    209.28x = 313.89 × 128.64
  4. Step 4: Simplify right side
    209.28x = 40,378.81
  5. Step 5: Solve for x
    x = 40,378.81/209.28
  6. Step 6: Final answer
    x = 192.94

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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.