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Finding the Fourth Proportional to 428.80, 643.81 and 409.22

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Solution

The fourth proportional to 428.80, 643.81 and 409.22 is: 614.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.80 : 643.81 = 409.22 : x
  2. Step 2: Convert to fraction form
    428.80/643.81 = 409.22/x
  3. Step 3: Cross multiply
    428.80x = 643.81 × 409.22
  4. Step 4: Simplify right side
    428.80x = 263,460.51
  5. Step 5: Solve for x
    x = 263,460.51/428.80
  6. Step 6: Final answer
    x = 614.42

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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.