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Finding the Fourth Proportional to 39.69, 54.72 and 31.35

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Solution

The fourth proportional to 39.69, 54.72 and 31.35 is: 43.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.69 : 54.72 = 31.35 : x
  2. Step 2: Convert to fraction form
    39.69/54.72 = 31.35/x
  3. Step 3: Cross multiply
    39.69x = 54.72 × 31.35
  4. Step 4: Simplify right side
    39.69x = 1,715.47
  5. Step 5: Solve for x
    x = 1,715.47/39.69
  6. Step 6: Final answer
    x = 43.22

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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.