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Finding the Fourth Proportional to 91.68, 126.21 and 81.30

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Solution

The fourth proportional to 91.68, 126.21 and 81.30 is: 111.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.68 : 126.21 = 81.30 : x
  2. Step 2: Convert to fraction form
    91.68/126.21 = 81.30/x
  3. Step 3: Cross multiply
    91.68x = 126.21 × 81.30
  4. Step 4: Simplify right side
    91.68x = 10,261.19
  5. Step 5: Solve for x
    x = 10,261.19/91.68
  6. Step 6: Final answer
    x = 111.92

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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.