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Finding the Fourth Proportional to 76.81, 105.90 and 70.66

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Solution

The fourth proportional to 76.81, 105.90 and 70.66 is: 97.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.81 : 105.90 = 70.66 : x
  2. Step 2: Convert to fraction form
    76.81/105.90 = 70.66/x
  3. Step 3: Cross multiply
    76.81x = 105.90 × 70.66
  4. Step 4: Simplify right side
    76.81x = 7,482.89
  5. Step 5: Solve for x
    x = 7,482.89/76.81
  6. Step 6: Final answer
    x = 97.42

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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.