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Finding the Fourth Proportional to 157.40, 217.20 and 91.91

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Solution

The fourth proportional to 157.40, 217.20 and 91.91 is: 126.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    157.40 : 217.20 = 91.91 : x
  2. Step 2: Convert to fraction form
    157.40/217.20 = 91.91/x
  3. Step 3: Cross multiply
    157.40x = 217.20 × 91.91
  4. Step 4: Simplify right side
    157.40x = 19,961.77
  5. Step 5: Solve for x
    x = 19,961.77/157.40
  6. Step 6: Final answer
    x = 126.83

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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.