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Finding the Fourth Proportional to 661.26, 912.55 and 399.43

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Solution

The fourth proportional to 661.26, 912.55 and 399.43 is: 551.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.26 : 912.55 = 399.43 : x
  2. Step 2: Convert to fraction form
    661.26/912.55 = 399.43/x
  3. Step 3: Cross multiply
    661.26x = 912.55 × 399.43
  4. Step 4: Simplify right side
    661.26x = 364,494.29
  5. Step 5: Solve for x
    x = 364,494.29/661.26
  6. Step 6: Final answer
    x = 551.21

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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.