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Finding the Fourth Proportional to 657.70, 986.43 and 428.21

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Solution

The fourth proportional to 657.70, 986.43 and 428.21 is: 642.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    657.70 : 986.43 = 428.21 : x
  2. Step 2: Convert to fraction form
    657.70/986.43 = 428.21/x
  3. Step 3: Cross multiply
    657.70x = 986.43 × 428.21
  4. Step 4: Simplify right side
    657.70x = 422,399.19
  5. Step 5: Solve for x
    x = 422,399.19/657.70
  6. Step 6: Final answer
    x = 642.24

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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.