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Finding the Fourth Proportional to 57.79, 86.71 and 21.22

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Solution

The fourth proportional to 57.79, 86.71 and 21.22 is: 31.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.79 : 86.71 = 21.22 : x
  2. Step 2: Convert to fraction form
    57.79/86.71 = 21.22/x
  3. Step 3: Cross multiply
    57.79x = 86.71 × 21.22
  4. Step 4: Simplify right side
    57.79x = 1,839.99
  5. Step 5: Solve for x
    x = 1,839.99/57.79
  6. Step 6: Final answer
    x = 31.84

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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.