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Finding the Fourth Proportional to 153.79, 212.13 and 121

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Solution

The fourth proportional to 153.79, 212.13 and 121 is: 166.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    153.79 : 212.13 = 121 : x
  2. Step 2: Convert to fraction form
    153.79/212.13 = 121/x
  3. Step 3: Cross multiply
    153.79x = 212.13 × 121
  4. Step 4: Simplify right side
    153.79x = 25,667.73
  5. Step 5: Solve for x
    x = 25,667.73/153.79
  6. Step 6: Final answer
    x = 166.90

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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.