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Finding the Fourth Proportional to 661.20, 912.48 and 399.30

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Solution

The fourth proportional to 661.20, 912.48 and 399.30 is: 551.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.20 : 912.48 = 399.30 : x
  2. Step 2: Convert to fraction form
    661.20/912.48 = 399.30/x
  3. Step 3: Cross multiply
    661.20x = 912.48 × 399.30
  4. Step 4: Simplify right side
    661.20x = 364,353.26
  5. Step 5: Solve for x
    x = 364,353.26/661.20
  6. Step 6: Final answer
    x = 551.05

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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.