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Finding the Fourth Proportional to 620.64, 856.47 and 399.63

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Solution

The fourth proportional to 620.64, 856.47 and 399.63 is: 551.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    620.64 : 856.47 = 399.63 : x
  2. Step 2: Convert to fraction form
    620.64/856.47 = 399.63/x
  3. Step 3: Cross multiply
    620.64x = 856.47 × 399.63
  4. Step 4: Simplify right side
    620.64x = 342,271.11
  5. Step 5: Solve for x
    x = 342,271.11/620.64
  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.