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Finding the Fourth Proportional to 421.90, 578.50 and 380.28

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Solution

The fourth proportional to 421.90, 578.50 and 380.28 is: 521.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.90 : 578.50 = 380.28 : x
  2. Step 2: Convert to fraction form
    421.90/578.50 = 380.28/x
  3. Step 3: Cross multiply
    421.90x = 578.50 × 380.28
  4. Step 4: Simplify right side
    421.90x = 219,991.98
  5. Step 5: Solve for x
    x = 219,991.98/421.90
  6. Step 6: Final answer
    x = 521.43

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.