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Finding the Fourth Proportional to 38.90, 53.72 and 31.68

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Solution

The fourth proportional to 38.90, 53.72 and 31.68 is: 43.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    38.90 : 53.72 = 31.68 : x
  2. Step 2: Convert to fraction form
    38.90/53.72 = 31.68/x
  3. Step 3: Cross multiply
    38.90x = 53.72 × 31.68
  4. Step 4: Simplify right side
    38.90x = 1,701.85
  5. Step 5: Solve for x
    x = 1,701.85/38.90
  6. Step 6: Final answer
    x = 43.75

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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.