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Finding the Fourth Proportional to 15.63, 21.55 and 12.91

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Solution

The fourth proportional to 15.63, 21.55 and 12.91 is: 17.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.63 : 21.55 = 12.91 : x
  2. Step 2: Convert to fraction form
    15.63/21.55 = 12.91/x
  3. Step 3: Cross multiply
    15.63x = 21.55 × 12.91
  4. Step 4: Simplify right side
    15.63x = 278.04
  5. Step 5: Solve for x
    x = 278.04/15.63
  6. Step 6: Final answer
    x = 17.79

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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.