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Finding the Fourth Proportional to 661.80, 912.78 and 399.54

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Solution

The fourth proportional to 661.80, 912.78 and 399.54 is: 551.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.80 : 912.78 = 399.54 : x
  2. Step 2: Convert to fraction form
    661.80/912.78 = 399.54/x
  3. Step 3: Cross multiply
    661.80x = 912.78 × 399.54
  4. Step 4: Simplify right side
    661.80x = 364,692.12
  5. Step 5: Solve for x
    x = 364,692.12/661.80
  6. Step 6: Final answer
    x = 551.06

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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.