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Finding the Fourth Proportional to 90.21, 134.81 and 87.14

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Solution

The fourth proportional to 90.21, 134.81 and 87.14 is: 130.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.21 : 134.81 = 87.14 : x
  2. Step 2: Convert to fraction form
    90.21/134.81 = 87.14/x
  3. Step 3: Cross multiply
    90.21x = 134.81 × 87.14
  4. Step 4: Simplify right side
    90.21x = 11,746.94
  5. Step 5: Solve for x
    x = 11,746.94/90.21
  6. Step 6: Final answer
    x = 130.21

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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.