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Finding the Fourth Proportional to 620.79, 856.74 and 399.60

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Solution

The fourth proportional to 620.79, 856.74 and 399.60 is: 551.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    620.79 : 856.74 = 399.60 : x
  2. Step 2: Convert to fraction form
    620.79/856.74 = 399.60/x
  3. Step 3: Cross multiply
    620.79x = 856.74 × 399.60
  4. Step 4: Simplify right side
    620.79x = 342,353.30
  5. Step 5: Solve for x
    x = 342,353.30/620.79
  6. Step 6: Final answer
    x = 551.48

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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.