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Finding the Fourth Proportional to 661.72, 913.17 and 399.69

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Solution

The fourth proportional to 661.72, 913.17 and 399.69 is: 551.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.72 : 913.17 = 399.69 : x
  2. Step 2: Convert to fraction form
    661.72/913.17 = 399.69/x
  3. Step 3: Cross multiply
    661.72x = 913.17 × 399.69
  4. Step 4: Simplify right side
    661.72x = 364,980.35
  5. Step 5: Solve for x
    x = 364,980.35/661.72
  6. Step 6: Final answer
    x = 551.56

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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.