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Finding the Fourth Proportional to 78.91, 108.66 and 69.64

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Solution

The fourth proportional to 78.91, 108.66 and 69.64 is: 95.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.91 : 108.66 = 69.64 : x
  2. Step 2: Convert to fraction form
    78.91/108.66 = 69.64/x
  3. Step 3: Cross multiply
    78.91x = 108.66 × 69.64
  4. Step 4: Simplify right side
    78.91x = 7,567.08
  5. Step 5: Solve for x
    x = 7,567.08/78.91
  6. Step 6: Final answer
    x = 95.90

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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.