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Finding the Fourth Proportional to 212.45, 318.74 and 90.74

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Solution

The fourth proportional to 212.45, 318.74 and 90.74 is: 136.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.45 : 318.74 = 90.74 : x
  2. Step 2: Convert to fraction form
    212.45/318.74 = 90.74/x
  3. Step 3: Cross multiply
    212.45x = 318.74 × 90.74
  4. Step 4: Simplify right side
    212.45x = 28,920.87
  5. Step 5: Solve for x
    x = 28,920.87/212.45
  6. Step 6: Final answer
    x = 136.13

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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.