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Finding the Fourth Proportional to 620.75, 856.26 and 399.78

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Solution

The fourth proportional to 620.75, 856.26 and 399.78 is: 551.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    620.75 : 856.26 = 399.78 : x
  2. Step 2: Convert to fraction form
    620.75/856.26 = 399.78/x
  3. Step 3: Cross multiply
    620.75x = 856.26 × 399.78
  4. Step 4: Simplify right side
    620.75x = 342,315.62
  5. Step 5: Solve for x
    x = 342,315.62/620.75
  6. Step 6: Final answer
    x = 551.45

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.