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Finding the Fourth Proportional to 209.81, 314.64 and 86.35

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Solution

The fourth proportional to 209.81, 314.64 and 86.35 is: 129.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    209.81 : 314.64 = 86.35 : x
  2. Step 2: Convert to fraction form
    209.81/314.64 = 86.35/x
  3. Step 3: Cross multiply
    209.81x = 314.64 × 86.35
  4. Step 4: Simplify right side
    209.81x = 27,169.16
  5. Step 5: Solve for x
    x = 27,169.16/209.81
  6. Step 6: Final answer
    x = 129.49

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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.