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Finding the Fourth Proportional to 309.72, 427.31 and 221.13

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Solution

The fourth proportional to 309.72, 427.31 and 221.13 is: 305.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    309.72 : 427.31 = 221.13 : x
  2. Step 2: Convert to fraction form
    309.72/427.31 = 221.13/x
  3. Step 3: Cross multiply
    309.72x = 427.31 × 221.13
  4. Step 4: Simplify right side
    309.72x = 94,490.78
  5. Step 5: Solve for x
    x = 94,490.78/309.72
  6. Step 6: Final answer
    x = 305.08

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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.