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Finding the Fourth Proportional to 120.87, 166.78 and 71.76

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Solution

The fourth proportional to 120.87, 166.78 and 71.76 is: 99.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.87 : 166.78 = 71.76 : x
  2. Step 2: Convert to fraction form
    120.87/166.78 = 71.76/x
  3. Step 3: Cross multiply
    120.87x = 166.78 × 71.76
  4. Step 4: Simplify right side
    120.87x = 11,968.13
  5. Step 5: Solve for x
    x = 11,968.13/120.87
  6. Step 6: Final answer
    x = 99.02

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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.