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Finding the Fourth Proportional to 998.86, 1,378.86 and 640.10

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Solution

The fourth proportional to 998.86, 1,378.86 and 640.10 is: 883.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    998.86 : 1,378.86 = 640.10 : x
  2. Step 2: Convert to fraction form
    998.86/1,378.86 = 640.10/x
  3. Step 3: Cross multiply
    998.86x = 1,378.86 × 640.10
  4. Step 4: Simplify right side
    998.86x = 882,608.29
  5. Step 5: Solve for x
    x = 882,608.29/998.86
  6. Step 6: Final answer
    x = 883.62

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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.