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Finding the Fourth Proportional to 21.92, 32.64 and 21

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Solution

The fourth proportional to 21.92, 32.64 and 21 is: 31.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.92 : 32.64 = 21 : x
  2. Step 2: Convert to fraction form
    21.92/32.64 = 21/x
  3. Step 3: Cross multiply
    21.92x = 32.64 × 21
  4. Step 4: Simplify right side
    21.92x = 685.44
  5. Step 5: Solve for x
    x = 685.44/21.92
  6. Step 6: Final answer
    x = 31.27

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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.