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Finding the Fourth Proportional to 665.43, 917.91 and 399.79

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Solution

The fourth proportional to 665.43, 917.91 and 399.79 is: 551.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    665.43 : 917.91 = 399.79 : x
  2. Step 2: Convert to fraction form
    665.43/917.91 = 399.79/x
  3. Step 3: Cross multiply
    665.43x = 917.91 × 399.79
  4. Step 4: Simplify right side
    665.43x = 366,971.24
  5. Step 5: Solve for x
    x = 366,971.24/665.43
  6. Step 6: Final answer
    x = 551.48

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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.