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Finding the Fourth Proportional to 31.65, 47.38 and 21.47

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Solution

The fourth proportional to 31.65, 47.38 and 21.47 is: 32.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.65 : 47.38 = 21.47 : x
  2. Step 2: Convert to fraction form
    31.65/47.38 = 21.47/x
  3. Step 3: Cross multiply
    31.65x = 47.38 × 21.47
  4. Step 4: Simplify right side
    31.65x = 1,017.31
  5. Step 5: Solve for x
    x = 1,017.31/31.65
  6. Step 6: Final answer
    x = 32.14

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.