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Finding the Fourth Proportional to 1,990.80, 2,986.20 and 1,638.45

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Solution

The fourth proportional to 1,990.80, 2,986.20 and 1,638.45 is: 2,457.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,990.80 : 2,986.20 = 1,638.45 : x
  2. Step 2: Convert to fraction form
    1,990.80/2,986.20 = 1,638.45/x
  3. Step 3: Cross multiply
    1,990.80x = 2,986.20 × 1,638.45
  4. Step 4: Simplify right side
    1,990.80x = 4,892,739.39
  5. Step 5: Solve for x
    x = 4,892,739.39/1,990.80
  6. Step 6: Final answer
    x = 2,457.68

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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.