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Finding the Fourth Proportional to 21.50, 31.99 and 20.92

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Solution

The fourth proportional to 21.50, 31.99 and 20.92 is: 31.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.50 : 31.99 = 20.92 : x
  2. Step 2: Convert to fraction form
    21.50/31.99 = 20.92/x
  3. Step 3: Cross multiply
    21.50x = 31.99 × 20.92
  4. Step 4: Simplify right side
    21.50x = 669.23
  5. Step 5: Solve for x
    x = 669.23/21.50
  6. Step 6: Final answer
    x = 31.13

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.