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Finding the Fourth Proportional to 989.31, 1,478.05 and 765.45

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Solution

The fourth proportional to 989.31, 1,478.05 and 765.45 is: 1,143.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.31 : 1,478.05 = 765.45 : x
  2. Step 2: Convert to fraction form
    989.31/1,478.05 = 765.45/x
  3. Step 3: Cross multiply
    989.31x = 1,478.05 × 765.45
  4. Step 4: Simplify right side
    989.31x = 1,131,371.46
  5. Step 5: Solve for x
    x = 1,131,371.46/989.31
  6. Step 6: Final answer
    x = 1,143.59

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.