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Finding the Fourth Proportional to 679.80, 1,021.01 and 643.01

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Solution

The fourth proportional to 679.80, 1,021.01 and 643.01 is: 965.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.80 : 1,021.01 = 643.01 : x
  2. Step 2: Convert to fraction form
    679.80/1,021.01 = 643.01/x
  3. Step 3: Cross multiply
    679.80x = 1,021.01 × 643.01
  4. Step 4: Simplify right side
    679.80x = 656,519.64
  5. Step 5: Solve for x
    x = 656,519.64/679.80
  6. Step 6: Final answer
    x = 965.75

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.