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Finding the Fourth Proportional to 209.86, 314.72 and 128.58

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Solution

The fourth proportional to 209.86, 314.72 and 128.58 is: 192.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.86 : 314.72 = 128.58 : x
  2. Step 2: Convert to fraction form
    209.86/314.72 = 128.58/x
  3. Step 3: Cross multiply
    209.86x = 314.72 × 128.58
  4. Step 4: Simplify right side
    209.86x = 40,466.70
  5. Step 5: Solve for x
    x = 40,466.70/209.86
  6. Step 6: Final answer
    x = 192.83

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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.