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Finding the Fourth Proportional to 100.50, 138.34 and 87.20

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Solution

The fourth proportional to 100.50, 138.34 and 87.20 is: 120.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.50 : 138.34 = 87.20 : x
  2. Step 2: Convert to fraction form
    100.50/138.34 = 87.20/x
  3. Step 3: Cross multiply
    100.50x = 138.34 × 87.20
  4. Step 4: Simplify right side
    100.50x = 12,063.12
  5. Step 5: Solve for x
    x = 12,063.12/100.50
  6. Step 6: Final answer
    x = 120.04

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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.