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Finding the Fourth Proportional to 661.40, 912.49 and 399.32

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Solution

The fourth proportional to 661.40, 912.49 and 399.32 is: 550.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.40 : 912.49 = 399.32 : x
  2. Step 2: Convert to fraction form
    661.40/912.49 = 399.32/x
  3. Step 3: Cross multiply
    661.40x = 912.49 × 399.32
  4. Step 4: Simplify right side
    661.40x = 364,369.95
  5. Step 5: Solve for x
    x = 364,369.95/661.40
  6. Step 6: Final answer
    x = 550.91

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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.