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Finding the Fourth Proportional to 90.42, 134.90 and 76.74

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Solution

The fourth proportional to 90.42, 134.90 and 76.74 is: 114.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.42 : 134.90 = 76.74 : x
  2. Step 2: Convert to fraction form
    90.42/134.90 = 76.74/x
  3. Step 3: Cross multiply
    90.42x = 134.90 × 76.74
  4. Step 4: Simplify right side
    90.42x = 10,351.84
  5. Step 5: Solve for x
    x = 10,351.84/90.42
  6. Step 6: Final answer
    x = 114.49

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.