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Finding the Fourth Proportional to 661.31, 912.75 and 399.32

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Solution

The fourth proportional to 661.31, 912.75 and 399.32 is: 551.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.31 : 912.75 = 399.32 : x
  2. Step 2: Convert to fraction form
    661.31/912.75 = 399.32/x
  3. Step 3: Cross multiply
    661.31x = 912.75 × 399.32
  4. Step 4: Simplify right side
    661.31x = 364,479.33
  5. Step 5: Solve for x
    x = 364,479.33/661.31
  6. Step 6: Final answer
    x = 551.15

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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.