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Finding the Fourth Proportional to 212.42, 318.90 and 139.32

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Solution

The fourth proportional to 212.42, 318.90 and 139.32 is: 209.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.42 : 318.90 = 139.32 : x
  2. Step 2: Convert to fraction form
    212.42/318.90 = 139.32/x
  3. Step 3: Cross multiply
    212.42x = 318.90 × 139.32
  4. Step 4: Simplify right side
    212.42x = 44,427.21
  5. Step 5: Solve for x
    x = 44,427.21/212.42
  6. Step 6: Final answer
    x = 209.15

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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.