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Finding the Fourth Proportional to 142.17, 212.91 and 87.90

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Solution

The fourth proportional to 142.17, 212.91 and 87.90 is: 131.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    142.17 : 212.91 = 87.90 : x
  2. Step 2: Convert to fraction form
    142.17/212.91 = 87.90/x
  3. Step 3: Cross multiply
    142.17x = 212.91 × 87.90
  4. Step 4: Simplify right side
    142.17x = 18,714.79
  5. Step 5: Solve for x
    x = 18,714.79/142.17
  6. Step 6: Final answer
    x = 131.64

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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.