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Finding the Fourth Proportional to 212.71, 318.91 and 115.15

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Solution

The fourth proportional to 212.71, 318.91 and 115.15 is: 172.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.71 : 318.91 = 115.15 : x
  2. Step 2: Convert to fraction form
    212.71/318.91 = 115.15/x
  3. Step 3: Cross multiply
    212.71x = 318.91 × 115.15
  4. Step 4: Simplify right side
    212.71x = 36,722.49
  5. Step 5: Solve for x
    x = 36,722.49/212.71
  6. Step 6: Final answer
    x = 172.64

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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.