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Finding the Fourth Proportional to 1.20, 1.80 and 0.31

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Solution

The fourth proportional to 1.20, 1.80 and 0.31 is: 0.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    1.20 : 1.80 = 0.31 : x
  2. Step 2: Convert to fraction form
    1.20/1.80 = 0.31/x
  3. Step 3: Cross multiply
    1.20x = 1.80 × 0.31
  4. Step 4: Simplify right side
    1.20x = 0.56
  5. Step 5: Solve for x
    x = 0.56/1.20
  6. Step 6: Final answer
    x = 0.47

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.