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Finding the Fourth Proportional to 212.40, 292.86 and 138.78

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Solution

The fourth proportional to 212.40, 292.86 and 138.78 is: 191.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    212.40 : 292.86 = 138.78 : x
  2. Step 2: Convert to fraction form
    212.40/292.86 = 138.78/x
  3. Step 3: Cross multiply
    212.40x = 292.86 × 138.78
  4. Step 4: Simplify right side
    212.40x = 40,643.11
  5. Step 5: Solve for x
    x = 40,643.11/212.40
  6. Step 6: Final answer
    x = 191.35

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.