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Finding the Fourth Proportional to 120.80, 166.70 and 85.79

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Solution

The fourth proportional to 120.80, 166.70 and 85.79 is: 118.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.80 : 166.70 = 85.79 : x
  2. Step 2: Convert to fraction form
    120.80/166.70 = 85.79/x
  3. Step 3: Cross multiply
    120.80x = 166.70 × 85.79
  4. Step 4: Simplify right side
    120.80x = 14,301.19
  5. Step 5: Solve for x
    x = 14,301.19/120.80
  6. Step 6: Final answer
    x = 118.39

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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.