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Finding the Fourth Proportional to 291.20, 401.60 and 221.28

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Solution

The fourth proportional to 291.20, 401.60 and 221.28 is: 305.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    291.20 : 401.60 = 221.28 : x
  2. Step 2: Convert to fraction form
    291.20/401.60 = 221.28/x
  3. Step 3: Cross multiply
    291.20x = 401.60 × 221.28
  4. Step 4: Simplify right side
    291.20x = 88,866.05
  5. Step 5: Solve for x
    x = 88,866.05/291.20
  6. Step 6: Final answer
    x = 305.17

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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.