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Finding the Fourth Proportional to 120.69, 166.59 and 99.90

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Solution

The fourth proportional to 120.69, 166.59 and 99.90 is: 137.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.69 : 166.59 = 99.90 : x
  2. Step 2: Convert to fraction form
    120.69/166.59 = 99.90/x
  3. Step 3: Cross multiply
    120.69x = 166.59 × 99.90
  4. Step 4: Simplify right side
    120.69x = 16,642.34
  5. Step 5: Solve for x
    x = 16,642.34/120.69
  6. Step 6: Final answer
    x = 137.89

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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.