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Finding the Fourth Proportional to 153.78, 212.23 and 87.40

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Solution

The fourth proportional to 153.78, 212.23 and 87.40 is: 120.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    153.78 : 212.23 = 87.40 : x
  2. Step 2: Convert to fraction form
    153.78/212.23 = 87.40/x
  3. Step 3: Cross multiply
    153.78x = 212.23 × 87.40
  4. Step 4: Simplify right side
    153.78x = 18,548.90
  5. Step 5: Solve for x
    x = 18,548.90/153.78
  6. Step 6: Final answer
    x = 120.62

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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.