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Finding the Fourth Proportional to 428.70, 643.61 and 275.25

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Solution

The fourth proportional to 428.70, 643.61 and 275.25 is: 413.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.70 : 643.61 = 275.25 : x
  2. Step 2: Convert to fraction form
    428.70/643.61 = 275.25/x
  3. Step 3: Cross multiply
    428.70x = 643.61 × 275.25
  4. Step 4: Simplify right side
    428.70x = 177,149.06
  5. Step 5: Solve for x
    x = 177,149.06/428.70
  6. Step 6: Final answer
    x = 413.23

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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.