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Finding the Fourth Proportional to 15.84, 21.80 and 15.12

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Solution

The fourth proportional to 15.84, 21.80 and 15.12 is: 20.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.84 : 21.80 = 15.12 : x
  2. Step 2: Convert to fraction form
    15.84/21.80 = 15.12/x
  3. Step 3: Cross multiply
    15.84x = 21.80 × 15.12
  4. Step 4: Simplify right side
    15.84x = 329.62
  5. Step 5: Solve for x
    x = 329.62/15.84
  6. Step 6: Final answer
    x = 20.81

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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.