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Finding the Fourth Proportional to 99, 136.40 and 90.72

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Solution

The fourth proportional to 99, 136.40 and 90.72 is: 124.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    99 : 136.40 = 90.72 : x
  2. Step 2: Convert to fraction form
    99/136.40 = 90.72/x
  3. Step 3: Cross multiply
    99x = 136.40 × 90.72
  4. Step 4: Simplify right side
    99x = 12,374.21
  5. Step 5: Solve for x
    x = 12,374.21/99
  6. Step 6: Final answer
    x = 124.99

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.