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Finding the Fourth Proportional to 157.81, 217.78 and 91.42

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Solution

The fourth proportional to 157.81, 217.78 and 91.42 is: 126.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    157.81 : 217.78 = 91.42 : x
  2. Step 2: Convert to fraction form
    157.81/217.78 = 91.42/x
  3. Step 3: Cross multiply
    157.81x = 217.78 × 91.42
  4. Step 4: Simplify right side
    157.81x = 19,908.67
  5. Step 5: Solve for x
    x = 19,908.67/157.81
  6. Step 6: Final answer
    x = 126.16

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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.