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Finding the Fourth Proportional to 769.38, 1,158.18 and 690

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Solution

The fourth proportional to 769.38, 1,158.18 and 690 is: 1,038.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    769.38 : 1,158.18 = 690 : x
  2. Step 2: Convert to fraction form
    769.38/1,158.18 = 690/x
  3. Step 3: Cross multiply
    769.38x = 1,158.18 × 690
  4. Step 4: Simplify right side
    769.38x = 799,144.20
  5. Step 5: Solve for x
    x = 799,144.20/769.38
  6. Step 6: Final answer
    x = 1,038.69

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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.