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Finding the Fourth Proportional to 689.78, 1,034.50 and 278.80

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Solution

The fourth proportional to 689.78, 1,034.50 and 278.80 is: 418.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.78 : 1,034.50 = 278.80 : x
  2. Step 2: Convert to fraction form
    689.78/1,034.50 = 278.80/x
  3. Step 3: Cross multiply
    689.78x = 1,034.50 × 278.80
  4. Step 4: Simplify right side
    689.78x = 288,412.03
  5. Step 5: Solve for x
    x = 288,412.03/689.78
  6. Step 6: Final answer
    x = 418.12

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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.