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Finding the Fourth Proportional to 153.90, 212.18 and 121.02

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Solution

The fourth proportional to 153.90, 212.18 and 121.02 is: 166.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    153.90 : 212.18 = 121.02 : x
  2. Step 2: Convert to fraction form
    153.90/212.18 = 121.02/x
  3. Step 3: Cross multiply
    153.90x = 212.18 × 121.02
  4. Step 4: Simplify right side
    153.90x = 25,678.02
  5. Step 5: Solve for x
    x = 25,678.02/153.90
  6. Step 6: Final answer
    x = 166.85

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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.