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Finding the Fourth Proportional to 39.81, 54.91 and 39

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Solution

The fourth proportional to 39.81, 54.91 and 39 is: 53.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.81 : 54.91 = 39 : x
  2. Step 2: Convert to fraction form
    39.81/54.91 = 39/x
  3. Step 3: Cross multiply
    39.81x = 54.91 × 39
  4. Step 4: Simplify right side
    39.81x = 2,141.49
  5. Step 5: Solve for x
    x = 2,141.49/39.81
  6. Step 6: Final answer
    x = 53.79

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1.5x scale

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.