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Finding the Fourth Proportional to 21.76, 30.04 and 15.21

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Solution

The fourth proportional to 21.76, 30.04 and 15.21 is: 21.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.76 : 30.04 = 15.21 : x
  2. Step 2: Convert to fraction form
    21.76/30.04 = 15.21/x
  3. Step 3: Cross multiply
    21.76x = 30.04 × 15.21
  4. Step 4: Simplify right side
    21.76x = 456.87
  5. Step 5: Solve for x
    x = 456.87/21.76
  6. Step 6: Final answer
    x = 21.00

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.