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Finding the Fourth Proportional to 661.90, 913.43 and 399.90

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Solution

The fourth proportional to 661.90, 913.43 and 399.90 is: 551.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.90 : 913.43 = 399.90 : x
  2. Step 2: Convert to fraction form
    661.90/913.43 = 399.90/x
  3. Step 3: Cross multiply
    661.90x = 913.43 × 399.90
  4. Step 4: Simplify right side
    661.90x = 365,280.66
  5. Step 5: Solve for x
    x = 365,280.66/661.90
  6. Step 6: Final answer
    x = 551.87

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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.