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Finding the Fourth Proportional to 120.42, 180.45 and 72.21

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Solution

The fourth proportional to 120.42, 180.45 and 72.21 is: 108.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.42 : 180.45 = 72.21 : x
  2. Step 2: Convert to fraction form
    120.42/180.45 = 72.21/x
  3. Step 3: Cross multiply
    120.42x = 180.45 × 72.21
  4. Step 4: Simplify right side
    120.42x = 13,030.29
  5. Step 5: Solve for x
    x = 13,030.29/120.42
  6. Step 6: Final answer
    x = 108.21

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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.