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Finding the Fourth Proportional to 84.21, 125.76 and 72.05

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Solution

The fourth proportional to 84.21, 125.76 and 72.05 is: 107.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.21 : 125.76 = 72.05 : x
  2. Step 2: Convert to fraction form
    84.21/125.76 = 72.05/x
  3. Step 3: Cross multiply
    84.21x = 125.76 × 72.05
  4. Step 4: Simplify right side
    84.21x = 9,061.01
  5. Step 5: Solve for x
    x = 9,061.01/84.21
  6. Step 6: Final answer
    x = 107.60

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.