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Finding the Fourth Proportional to 989.70, 1,486.85 and 620.64

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Solution

The fourth proportional to 989.70, 1,486.85 and 620.64 is: 932.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.70 : 1,486.85 = 620.64 : x
  2. Step 2: Convert to fraction form
    989.70/1,486.85 = 620.64/x
  3. Step 3: Cross multiply
    989.70x = 1,486.85 × 620.64
  4. Step 4: Simplify right side
    989.70x = 922,795.48
  5. Step 5: Solve for x
    x = 922,795.48/989.70
  6. Step 6: Final answer
    x = 932.40

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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.