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Finding the Fourth Proportional to 153.99, 212.49 and 121.20

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Solution

The fourth proportional to 153.99, 212.49 and 121.20 is: 167.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    153.99 : 212.49 = 121.20 : x
  2. Step 2: Convert to fraction form
    153.99/212.49 = 121.20/x
  3. Step 3: Cross multiply
    153.99x = 212.49 × 121.20
  4. Step 4: Simplify right side
    153.99x = 25,753.79
  5. Step 5: Solve for x
    x = 25,753.79/153.99
  6. Step 6: Final answer
    x = 167.24

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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.