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Finding the Fourth Proportional to 39.84, 54.75 and 31.20

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Solution

The fourth proportional to 39.84, 54.75 and 31.20 is: 42.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.84 : 54.75 = 31.20 : x
  2. Step 2: Convert to fraction form
    39.84/54.75 = 31.20/x
  3. Step 3: Cross multiply
    39.84x = 54.75 × 31.20
  4. Step 4: Simplify right side
    39.84x = 1,708.20
  5. Step 5: Solve for x
    x = 1,708.20/39.84
  6. Step 6: Final answer
    x = 42.88

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.