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Finding the Fourth Proportional to 91.90, 126.21 and 85.56

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Solution

The fourth proportional to 91.90, 126.21 and 85.56 is: 117.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.90 : 126.21 = 85.56 : x
  2. Step 2: Convert to fraction form
    91.90/126.21 = 85.56/x
  3. Step 3: Cross multiply
    91.90x = 126.21 × 85.56
  4. Step 4: Simplify right side
    91.90x = 10,798.53
  5. Step 5: Solve for x
    x = 10,798.53/91.90
  6. Step 6: Final answer
    x = 117.50

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.