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Finding the Fourth Proportional to 90, 133.98 and 87.72

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Solution

The fourth proportional to 90, 133.98 and 87.72 is: 130.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    90 : 133.98 = 87.72 : x
  2. Step 2: Convert to fraction form
    90/133.98 = 87.72/x
  3. Step 3: Cross multiply
    90x = 133.98 × 87.72
  4. Step 4: Simplify right side
    90x = 11,752.73
  5. Step 5: Solve for x
    x = 11,752.73/90
  6. Step 6: Final answer
    x = 130.59

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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.