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Finding the Fourth Proportional to 120.12, 165.72 and 87

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Solution

The fourth proportional to 120.12, 165.72 and 87 is: 120.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.12 : 165.72 = 87 : x
  2. Step 2: Convert to fraction form
    120.12/165.72 = 87/x
  3. Step 3: Cross multiply
    120.12x = 165.72 × 87
  4. Step 4: Simplify right side
    120.12x = 14,417.64
  5. Step 5: Solve for x
    x = 14,417.64/120.12
  6. Step 6: Final answer
    x = 120.03

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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.