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Finding the Fourth Proportional to 120.40, 165.97 and 87.60

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Solution

The fourth proportional to 120.40, 165.97 and 87.60 is: 120.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.40 : 165.97 = 87.60 : x
  2. Step 2: Convert to fraction form
    120.40/165.97 = 87.60/x
  3. Step 3: Cross multiply
    120.40x = 165.97 × 87.60
  4. Step 4: Simplify right side
    120.40x = 14,538.97
  5. Step 5: Solve for x
    x = 14,538.97/120.40
  6. Step 6: Final answer
    x = 120.76

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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.