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Finding the Fourth Proportional to 643.80, 889.29 and 505.65

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Solution

The fourth proportional to 643.80, 889.29 and 505.65 is: 698.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.80 : 889.29 = 505.65 : x
  2. Step 2: Convert to fraction form
    643.80/889.29 = 505.65/x
  3. Step 3: Cross multiply
    643.80x = 889.29 × 505.65
  4. Step 4: Simplify right side
    643.80x = 449,669.49
  5. Step 5: Solve for x
    x = 449,669.49/643.80
  6. Step 6: Final answer
    x = 698.46

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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.