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Finding the Fourth Proportional to 120.90, 166.86 and 71.80

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Solution

The fourth proportional to 120.90, 166.86 and 71.80 is: 99.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.90 : 166.86 = 71.80 : x
  2. Step 2: Convert to fraction form
    120.90/166.86 = 71.80/x
  3. Step 3: Cross multiply
    120.90x = 166.86 × 71.80
  4. Step 4: Simplify right side
    120.90x = 11,980.55
  5. Step 5: Solve for x
    x = 11,980.55/120.90
  6. Step 6: Final answer
    x = 99.09

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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.