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Finding the Fourth Proportional to 212.39, 318.64 and 121.15

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Solution

The fourth proportional to 212.39, 318.64 and 121.15 is: 181.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.39 : 318.64 = 121.15 : x
  2. Step 2: Convert to fraction form
    212.39/318.64 = 121.15/x
  3. Step 3: Cross multiply
    212.39x = 318.64 × 121.15
  4. Step 4: Simplify right side
    212.39x = 38,603.24
  5. Step 5: Solve for x
    x = 38,603.24/212.39
  6. Step 6: Final answer
    x = 181.76

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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.