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Finding the Fourth Proportional to 209.61, 314.13 and 128.43

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Solution

The fourth proportional to 209.61, 314.13 and 128.43 is: 192.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.61 : 314.13 = 128.43 : x
  2. Step 2: Convert to fraction form
    209.61/314.13 = 128.43/x
  3. Step 3: Cross multiply
    209.61x = 314.13 × 128.43
  4. Step 4: Simplify right side
    209.61x = 40,343.72
  5. Step 5: Solve for x
    x = 40,343.72/209.61
  6. Step 6: Final answer
    x = 192.47

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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.