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Finding the Fourth Proportional to 91.31, 126.08 and 66.78

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Solution

The fourth proportional to 91.31, 126.08 and 66.78 is: 92.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.31 : 126.08 = 66.78 : x
  2. Step 2: Convert to fraction form
    91.31/126.08 = 66.78/x
  3. Step 3: Cross multiply
    91.31x = 126.08 × 66.78
  4. Step 4: Simplify right side
    91.31x = 8,419.29
  5. Step 5: Solve for x
    x = 8,419.29/91.31
  6. Step 6: Final answer
    x = 92.21

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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.