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Finding the Fourth Proportional to 142.12, 212.88 and 87.11

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Solution

The fourth proportional to 142.12, 212.88 and 87.11 is: 130.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.12 : 212.88 = 87.11 : x
  2. Step 2: Convert to fraction form
    142.12/212.88 = 87.11/x
  3. Step 3: Cross multiply
    142.12x = 212.88 × 87.11
  4. Step 4: Simplify right side
    142.12x = 18,544.74
  5. Step 5: Solve for x
    x = 18,544.74/142.12
  6. Step 6: Final answer
    x = 130.48

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.