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Finding the Fourth Proportional to 0.39, 0.54 and 0.21

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Solution

The fourth proportional to 0.39, 0.54 and 0.21 is: 0.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    0.39 : 0.54 = 0.21 : x
  2. Step 2: Convert to fraction form
    0.39/0.54 = 0.21/x
  3. Step 3: Cross multiply
    0.39x = 0.54 × 0.21
  4. Step 4: Simplify right side
    0.39x = 0.11
  5. Step 5: Solve for x
    x = 0.11/0.39
  6. Step 6: Final answer
    x = 0.29

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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.