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Finding the Fourth Proportional to 120.78, 166.62 and 87.16

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Solution

The fourth proportional to 120.78, 166.62 and 87.16 is: 120.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.78 : 166.62 = 87.16 : x
  2. Step 2: Convert to fraction form
    120.78/166.62 = 87.16/x
  3. Step 3: Cross multiply
    120.78x = 166.62 × 87.16
  4. Step 4: Simplify right side
    120.78x = 14,522.60
  5. Step 5: Solve for x
    x = 14,522.60/120.78
  6. Step 6: Final answer
    x = 120.24

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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.