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Finding the Fourth Proportional to 209.16, 313.02 and 128.16

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Solution

The fourth proportional to 209.16, 313.02 and 128.16 is: 191.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.16 : 313.02 = 128.16 : x
  2. Step 2: Convert to fraction form
    209.16/313.02 = 128.16/x
  3. Step 3: Cross multiply
    209.16x = 313.02 × 128.16
  4. Step 4: Simplify right side
    209.16x = 40,116.64
  5. Step 5: Solve for x
    x = 40,116.64/209.16
  6. Step 6: Final answer
    x = 191.80

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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.