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Finding the Fourth Proportional to 70.80, 105.78 and 66.75

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Solution

The fourth proportional to 70.80, 105.78 and 66.75 is: 99.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    70.80 : 105.78 = 66.75 : x
  2. Step 2: Convert to fraction form
    70.80/105.78 = 66.75/x
  3. Step 3: Cross multiply
    70.80x = 105.78 × 66.75
  4. Step 4: Simplify right side
    70.80x = 7,060.82
  5. Step 5: Solve for x
    x = 7,060.82/70.80
  6. Step 6: Final answer
    x = 99.73

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.