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Finding the Fourth Proportional to 689.26, 1,039.20 and 642.28

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Solution

The fourth proportional to 689.26, 1,039.20 and 642.28 is: 968.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.26 : 1,039.20 = 642.28 : x
  2. Step 2: Convert to fraction form
    689.26/1,039.20 = 642.28/x
  3. Step 3: Cross multiply
    689.26x = 1,039.20 × 642.28
  4. Step 4: Simplify right side
    689.26x = 667,457.38
  5. Step 5: Solve for x
    x = 667,457.38/689.26
  6. Step 6: Final answer
    x = 968.37

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.