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Finding the Fourth Proportional to 1,327.60, 1,990.40 and 678.80

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Solution

The fourth proportional to 1,327.60, 1,990.40 and 678.80 is: 1,017.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,327.60 : 1,990.40 = 678.80 : x
  2. Step 2: Convert to fraction form
    1,327.60/1,990.40 = 678.80/x
  3. Step 3: Cross multiply
    1,327.60x = 1,990.40 × 678.80
  4. Step 4: Simplify right side
    1,327.60x = 1,351,083.52
  5. Step 5: Solve for x
    x = 1,351,083.52/1,327.60
  6. Step 6: Final answer
    x = 1,017.69

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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.