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Finding the Fourth Proportional to 79.85, 119.70 and 31.79

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Solution

The fourth proportional to 79.85, 119.70 and 31.79 is: 47.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.85 : 119.70 = 31.79 : x
  2. Step 2: Convert to fraction form
    79.85/119.70 = 31.79/x
  3. Step 3: Cross multiply
    79.85x = 119.70 × 31.79
  4. Step 4: Simplify right side
    79.85x = 3,804.66
  5. Step 5: Solve for x
    x = 3,804.66/79.85
  6. Step 6: Final answer
    x = 47.65

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.