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Finding the Fourth Proportional to 78.24, 108.12 and 66

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Solution

The fourth proportional to 78.24, 108.12 and 66 is: 91.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.24 : 108.12 = 66 : x
  2. Step 2: Convert to fraction form
    78.24/108.12 = 66/x
  3. Step 3: Cross multiply
    78.24x = 108.12 × 66
  4. Step 4: Simplify right side
    78.24x = 7,135.92
  5. Step 5: Solve for x
    x = 7,135.92/78.24
  6. Step 6: Final answer
    x = 91.21

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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.