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Finding the Fourth Proportional to 661.38, 912.69 and 399.42

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Solution

The fourth proportional to 661.38, 912.69 and 399.42 is: 551.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.38 : 912.69 = 399.42 : x
  2. Step 2: Convert to fraction form
    661.38/912.69 = 399.42/x
  3. Step 3: Cross multiply
    661.38x = 912.69 × 399.42
  4. Step 4: Simplify right side
    661.38x = 364,546.64
  5. Step 5: Solve for x
    x = 364,546.64/661.38
  6. Step 6: Final answer
    x = 551.19

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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.