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Finding the Fourth Proportional to 153.19, 211.39 and 86.81

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Solution

The fourth proportional to 153.19, 211.39 and 86.81 is: 119.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    153.19 : 211.39 = 86.81 : x
  2. Step 2: Convert to fraction form
    153.19/211.39 = 86.81/x
  3. Step 3: Cross multiply
    153.19x = 211.39 × 86.81
  4. Step 4: Simplify right side
    153.19x = 18,349.49
  5. Step 5: Solve for x
    x = 18,349.49/153.19
  6. Step 6: Final answer
    x = 119.78

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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.