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Finding the Fourth Proportional to 21.63, 29.85 and 13

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Solution

The fourth proportional to 21.63, 29.85 and 13 is: 17.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.63 : 29.85 = 13 : x
  2. Step 2: Convert to fraction form
    21.63/29.85 = 13/x
  3. Step 3: Cross multiply
    21.63x = 29.85 × 13
  4. Step 4: Simplify right side
    21.63x = 387.99
  5. Step 5: Solve for x
    x = 387.99/21.63
  6. Step 6: Final answer
    x = 17.94

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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.