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Finding the Fourth Proportional to 209.15, 313.68 and 72.20

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Solution

The fourth proportional to 209.15, 313.68 and 72.20 is: 108.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.15 : 313.68 = 72.20 : x
  2. Step 2: Convert to fraction form
    209.15/313.68 = 72.20/x
  3. Step 3: Cross multiply
    209.15x = 313.68 × 72.20
  4. Step 4: Simplify right side
    209.15x = 22,646.13
  5. Step 5: Solve for x
    x = 22,646.13/209.15
  6. Step 6: Final answer
    x = 108.28

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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.