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Finding the Fourth Proportional to 665.07, 991.26 and 645.21

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Solution

The fourth proportional to 665.07, 991.26 and 645.21 is: 961.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    665.07 : 991.26 = 645.21 : x
  2. Step 2: Convert to fraction form
    665.07/991.26 = 645.21/x
  3. Step 3: Cross multiply
    665.07x = 991.26 × 645.21
  4. Step 4: Simplify right side
    665.07x = 639,570.86
  5. Step 5: Solve for x
    x = 639,570.86/665.07
  6. Step 6: Final answer
    x = 961.66

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.