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Finding the Fourth Proportional to 21.15, 31.66 and 19.75

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Solution

The fourth proportional to 21.15, 31.66 and 19.75 is: 29.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.15 : 31.66 = 19.75 : x
  2. Step 2: Convert to fraction form
    21.15/31.66 = 19.75/x
  3. Step 3: Cross multiply
    21.15x = 31.66 × 19.75
  4. Step 4: Simplify right side
    21.15x = 625.29
  5. Step 5: Solve for x
    x = 625.29/21.15
  6. Step 6: Final answer
    x = 29.56

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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.