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Finding the Fourth Proportional to 120.60, 166.40 and 85.72

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Solution

The fourth proportional to 120.60, 166.40 and 85.72 is: 118.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.60 : 166.40 = 85.72 : x
  2. Step 2: Convert to fraction form
    120.60/166.40 = 85.72/x
  3. Step 3: Cross multiply
    120.60x = 166.40 × 85.72
  4. Step 4: Simplify right side
    120.60x = 14,263.81
  5. Step 5: Solve for x
    x = 14,263.81/120.60
  6. Step 6: Final answer
    x = 118.27

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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.