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Finding the Fourth Proportional to 153.90, 212.12 and 122.70

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Solution

The fourth proportional to 153.90, 212.12 and 122.70 is: 169.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    153.90 : 212.12 = 122.70 : x
  2. Step 2: Convert to fraction form
    153.90/212.12 = 122.70/x
  3. Step 3: Cross multiply
    153.90x = 212.12 × 122.70
  4. Step 4: Simplify right side
    153.90x = 26,026.51
  5. Step 5: Solve for x
    x = 26,026.51/153.90
  6. Step 6: Final answer
    x = 169.11

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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.