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Finding the Fourth Proportional to 78.42, 107.98 and 66.74

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Solution

The fourth proportional to 78.42, 107.98 and 66.74 is: 91.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.42 : 107.98 = 66.74 : x
  2. Step 2: Convert to fraction form
    78.42/107.98 = 66.74/x
  3. Step 3: Cross multiply
    78.42x = 107.98 × 66.74
  4. Step 4: Simplify right side
    78.42x = 7,206.59
  5. Step 5: Solve for x
    x = 7,206.59/78.42
  6. Step 6: Final answer
    x = 91.90

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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.