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Finding the Fourth Proportional to 21.18, 29.21 and 15.74

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Solution

The fourth proportional to 21.18, 29.21 and 15.74 is: 21.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.18 : 29.21 = 15.74 : x
  2. Step 2: Convert to fraction form
    21.18/29.21 = 15.74/x
  3. Step 3: Cross multiply
    21.18x = 29.21 × 15.74
  4. Step 4: Simplify right side
    21.18x = 459.54
  5. Step 5: Solve for x
    x = 459.54/21.18
  6. Step 6: Final answer
    x = 21.70

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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.