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Finding the Fourth Proportional to 154.40, 212.88 and 121.28

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Solution

The fourth proportional to 154.40, 212.88 and 121.28 is: 167.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    154.40 : 212.88 = 121.28 : x
  2. Step 2: Convert to fraction form
    154.40/212.88 = 121.28/x
  3. Step 3: Cross multiply
    154.40x = 212.88 × 121.28
  4. Step 4: Simplify right side
    154.40x = 25,818.09
  5. Step 5: Solve for x
    x = 25,818.09/154.40
  6. Step 6: Final answer
    x = 167.22

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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.