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Finding the Fourth Proportional to 120.40, 166.20 and 99.64

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Solution

The fourth proportional to 120.40, 166.20 and 99.64 is: 137.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.40 : 166.20 = 99.64 : x
  2. Step 2: Convert to fraction form
    120.40/166.20 = 99.64/x
  3. Step 3: Cross multiply
    120.40x = 166.20 × 99.64
  4. Step 4: Simplify right side
    120.40x = 16,560.17
  5. Step 5: Solve for x
    x = 16,560.17/120.40
  6. Step 6: Final answer
    x = 137.54

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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.