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Finding the Fourth Proportional to 90.39, 135.47 and 42.20

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Solution

The fourth proportional to 90.39, 135.47 and 42.20 is: 63.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.39 : 135.47 = 42.20 : x
  2. Step 2: Convert to fraction form
    90.39/135.47 = 42.20/x
  3. Step 3: Cross multiply
    90.39x = 135.47 × 42.20
  4. Step 4: Simplify right side
    90.39x = 5,715.95
  5. Step 5: Solve for x
    x = 5,715.95/90.39
  6. Step 6: Final answer
    x = 63.24

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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.