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Finding the Fourth Proportional to 120.90, 181.30 and 86.88

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Solution

The fourth proportional to 120.90, 181.30 and 86.88 is: 130.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.90 : 181.30 = 86.88 : x
  2. Step 2: Convert to fraction form
    120.90/181.30 = 86.88/x
  3. Step 3: Cross multiply
    120.90x = 181.30 × 86.88
  4. Step 4: Simplify right side
    120.90x = 15,751.34
  5. Step 5: Solve for x
    x = 15,751.34/120.90
  6. Step 6: Final answer
    x = 130.28

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.