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Finding the Fourth Proportional to 620.71, 856.45 and 399.63

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Solution

The fourth proportional to 620.71, 856.45 and 399.63 is: 551.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    620.71 : 856.45 = 399.63 : x
  2. Step 2: Convert to fraction form
    620.71/856.45 = 399.63/x
  3. Step 3: Cross multiply
    620.71x = 856.45 × 399.63
  4. Step 4: Simplify right side
    620.71x = 342,266.82
  5. Step 5: Solve for x
    x = 342,266.82/620.71
  6. Step 6: Final answer
    x = 551.41

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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.