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Finding the Fourth Proportional to 21.58, 29.76 and 15.43

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Solution

The fourth proportional to 21.58, 29.76 and 15.43 is: 21.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.58 : 29.76 = 15.43 : x
  2. Step 2: Convert to fraction form
    21.58/29.76 = 15.43/x
  3. Step 3: Cross multiply
    21.58x = 29.76 × 15.43
  4. Step 4: Simplify right side
    21.58x = 459.20
  5. Step 5: Solve for x
    x = 459.20/21.58
  6. Step 6: Final answer
    x = 21.28

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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.