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Finding the Fourth Proportional to 85.79, 117.86 and 71.21

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Solution

The fourth proportional to 85.79, 117.86 and 71.21 is: 97.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.79 : 117.86 = 71.21 : x
  2. Step 2: Convert to fraction form
    85.79/117.86 = 71.21/x
  3. Step 3: Cross multiply
    85.79x = 117.86 × 71.21
  4. Step 4: Simplify right side
    85.79x = 8,392.75
  5. Step 5: Solve for x
    x = 8,392.75/85.79
  6. Step 6: Final answer
    x = 97.83

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.