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Finding the Fourth Proportional to 661.64, 913.19 and 399.80

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Solution

The fourth proportional to 661.64, 913.19 and 399.80 is: 551.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.64 : 913.19 = 399.80 : x
  2. Step 2: Convert to fraction form
    661.64/913.19 = 399.80/x
  3. Step 3: Cross multiply
    661.64x = 913.19 × 399.80
  4. Step 4: Simplify right side
    661.64x = 365,086.80
  5. Step 5: Solve for x
    x = 365,086.80/661.64
  6. Step 6: Final answer
    x = 551.79

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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.