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Finding the Fourth Proportional to 78.49, 108.30 and 66.81

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Solution

The fourth proportional to 78.49, 108.30 and 66.81 is: 92.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.49 : 108.30 = 66.81 : x
  2. Step 2: Convert to fraction form
    78.49/108.30 = 66.81/x
  3. Step 3: Cross multiply
    78.49x = 108.30 × 66.81
  4. Step 4: Simplify right side
    78.49x = 7,235.52
  5. Step 5: Solve for x
    x = 7,235.52/78.49
  6. Step 6: Final answer
    x = 92.18

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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.