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Finding the Fourth Proportional to 90.21, 135.42 and 54.23

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Solution

The fourth proportional to 90.21, 135.42 and 54.23 is: 81.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.21 : 135.42 = 54.23 : x
  2. Step 2: Convert to fraction form
    90.21/135.42 = 54.23/x
  3. Step 3: Cross multiply
    90.21x = 135.42 × 54.23
  4. Step 4: Simplify right side
    90.21x = 7,343.15
  5. Step 5: Solve for x
    x = 7,343.15/90.21
  6. Step 6: Final answer
    x = 81.40

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.