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Finding the Fourth Proportional to 21.16, 31.75 and 13.57

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Solution

The fourth proportional to 21.16, 31.75 and 13.57 is: 20.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.16 : 31.75 = 13.57 : x
  2. Step 2: Convert to fraction form
    21.16/31.75 = 13.57/x
  3. Step 3: Cross multiply
    21.16x = 31.75 × 13.57
  4. Step 4: Simplify right side
    21.16x = 430.73
  5. Step 5: Solve for x
    x = 430.73/21.16
  6. Step 6: Final answer
    x = 20.35

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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.