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Finding the Fourth Proportional to 21.60, 29.76 and 21

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Solution

The fourth proportional to 21.60, 29.76 and 21 is: 28.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.60 : 29.76 = 21 : x
  2. Step 2: Convert to fraction form
    21.60/29.76 = 21/x
  3. Step 3: Cross multiply
    21.60x = 29.76 × 21
  4. Step 4: Simplify right side
    21.60x = 624.96
  5. Step 5: Solve for x
    x = 624.96/21.60
  6. Step 6: Final answer
    x = 28.93

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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.