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Finding the Fourth Proportional to 153.90, 212.38 and 86.61

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Solution

The fourth proportional to 153.90, 212.38 and 86.61 is: 119.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    153.90 : 212.38 = 86.61 : x
  2. Step 2: Convert to fraction form
    153.90/212.38 = 86.61/x
  3. Step 3: Cross multiply
    153.90x = 212.38 × 86.61
  4. Step 4: Simplify right side
    153.90x = 18,393.62
  5. Step 5: Solve for x
    x = 18,393.62/153.90
  6. Step 6: Final answer
    x = 119.52

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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.