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Finding the Fourth Proportional to 39.79, 54.91 and 31.66

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Solution

The fourth proportional to 39.79, 54.91 and 31.66 is: 43.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.79 : 54.91 = 31.66 : x
  2. Step 2: Convert to fraction form
    39.79/54.91 = 31.66/x
  3. Step 3: Cross multiply
    39.79x = 54.91 × 31.66
  4. Step 4: Simplify right side
    39.79x = 1,738.45
  5. Step 5: Solve for x
    x = 1,738.45/39.79
  6. Step 6: Final answer
    x = 43.69

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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.