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Finding the Fourth Proportional to 212.61, 318.91 and 90.79

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Solution

The fourth proportional to 212.61, 318.91 and 90.79 is: 136.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.61 : 318.91 = 90.79 : x
  2. Step 2: Convert to fraction form
    212.61/318.91 = 90.79/x
  3. Step 3: Cross multiply
    212.61x = 318.91 × 90.79
  4. Step 4: Simplify right side
    212.61x = 28,953.38
  5. Step 5: Solve for x
    x = 28,953.38/212.61
  6. Step 6: Final answer
    x = 136.18

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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.