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Finding the Fourth Proportional to 15.61, 21.51 and 11.51

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Solution

The fourth proportional to 15.61, 21.51 and 11.51 is: 15.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.61 : 21.51 = 11.51 : x
  2. Step 2: Convert to fraction form
    15.61/21.51 = 11.51/x
  3. Step 3: Cross multiply
    15.61x = 21.51 × 11.51
  4. Step 4: Simplify right side
    15.61x = 247.56
  5. Step 5: Solve for x
    x = 247.56/15.61
  6. Step 6: Final answer
    x = 15.86

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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.