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Finding the Fourth Proportional to 209.18, 313.70 and 85.75

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Solution

The fourth proportional to 209.18, 313.70 and 85.75 is: 128.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.18 : 313.70 = 85.75 : x
  2. Step 2: Convert to fraction form
    209.18/313.70 = 85.75/x
  3. Step 3: Cross multiply
    209.18x = 313.70 × 85.75
  4. Step 4: Simplify right side
    209.18x = 26,899.78
  5. Step 5: Solve for x
    x = 26,899.78/209.18
  6. Step 6: Final answer
    x = 128.60

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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.