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Finding the Fourth Proportional to 15.39, 21.20 and 14.74

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Solution

The fourth proportional to 15.39, 21.20 and 14.74 is: 20.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.39 : 21.20 = 14.74 : x
  2. Step 2: Convert to fraction form
    15.39/21.20 = 14.74/x
  3. Step 3: Cross multiply
    15.39x = 21.20 × 14.74
  4. Step 4: Simplify right side
    15.39x = 312.49
  5. Step 5: Solve for x
    x = 312.49/15.39
  6. Step 6: Final answer
    x = 20.30

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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.