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Finding the Fourth Proportional to 153.20, 211.40 and 87.70

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Solution

The fourth proportional to 153.20, 211.40 and 87.70 is: 121.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    153.20 : 211.40 = 87.70 : x
  2. Step 2: Convert to fraction form
    153.20/211.40 = 87.70/x
  3. Step 3: Cross multiply
    153.20x = 211.40 × 87.70
  4. Step 4: Simplify right side
    153.20x = 18,539.78
  5. Step 5: Solve for x
    x = 18,539.78/153.20
  6. Step 6: Final answer
    x = 121.02

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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.