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Finding the Fourth Proportional to 21.25, 31.70 and 20.49

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Solution

The fourth proportional to 21.25, 31.70 and 20.49 is: 30.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.25 : 31.70 = 20.49 : x
  2. Step 2: Convert to fraction form
    21.25/31.70 = 20.49/x
  3. Step 3: Cross multiply
    21.25x = 31.70 × 20.49
  4. Step 4: Simplify right side
    21.25x = 649.53
  5. Step 5: Solve for x
    x = 649.53/21.25
  6. Step 6: Final answer
    x = 30.57

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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.