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Finding the Fourth Proportional to 15.67, 21.62 and 12.90

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Solution

The fourth proportional to 15.67, 21.62 and 12.90 is: 17.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.67 : 21.62 = 12.90 : x
  2. Step 2: Convert to fraction form
    15.67/21.62 = 12.90/x
  3. Step 3: Cross multiply
    15.67x = 21.62 × 12.90
  4. Step 4: Simplify right side
    15.67x = 278.93
  5. Step 5: Solve for x
    x = 278.93/15.67
  6. Step 6: Final answer
    x = 17.80

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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.