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Finding the Fourth Proportional to 689.71, 951.79 and 420.45

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Solution

The fourth proportional to 689.71, 951.79 and 420.45 is: 580.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.71 : 951.79 = 420.45 : x
  2. Step 2: Convert to fraction form
    689.71/951.79 = 420.45/x
  3. Step 3: Cross multiply
    689.71x = 951.79 × 420.45
  4. Step 4: Simplify right side
    689.71x = 400,175.49
  5. Step 5: Solve for x
    x = 400,175.49/689.71
  6. Step 6: Final answer
    x = 580.21

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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.