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Finding the Fourth Proportional to 1.28, 1.91 and 0.43

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Solution

The fourth proportional to 1.28, 1.91 and 0.43 is: 0.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    1.28 : 1.91 = 0.43 : x
  2. Step 2: Convert to fraction form
    1.28/1.91 = 0.43/x
  3. Step 3: Cross multiply
    1.28x = 1.91 × 0.43
  4. Step 4: Simplify right side
    1.28x = 0.82
  5. Step 5: Solve for x
    x = 0.82/1.28
  6. Step 6: Final answer
    x = 0.64

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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.