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Finding the Fourth Proportional to 421.26, 628.45 and 415.80

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Solution

The fourth proportional to 421.26, 628.45 and 415.80 is: 620.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.26 : 628.45 = 415.80 : x
  2. Step 2: Convert to fraction form
    421.26/628.45 = 415.80/x
  3. Step 3: Cross multiply
    421.26x = 628.45 × 415.80
  4. Step 4: Simplify right side
    421.26x = 261,309.51
  5. Step 5: Solve for x
    x = 261,309.51/421.26
  6. Step 6: Final answer
    x = 620.30

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.