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Finding the Fourth Proportional to 1.21, 1.81 and 0.91

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Solution

The fourth proportional to 1.21, 1.81 and 0.91 is: 1.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    1.21 : 1.81 = 0.91 : x
  2. Step 2: Convert to fraction form
    1.21/1.81 = 0.91/x
  3. Step 3: Cross multiply
    1.21x = 1.81 × 0.91
  4. Step 4: Simplify right side
    1.21x = 1.64
  5. Step 5: Solve for x
    x = 1.64/1.21
  6. Step 6: Final answer
    x = 1.36

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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.