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Finding the Fourth Proportional to 998.40, 1,399.20 and 998.40

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Solution

The fourth proportional to 998.40, 1,399.20 and 998.40 is: 1,399.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    998.40 : 1,399.20 = 998.40 : x
  2. Step 2: Convert to fraction form
    998.40/1,399.20 = 998.40/x
  3. Step 3: Cross multiply
    998.40x = 1,399.20 × 998.40
  4. Step 4: Simplify right side
    998.40x = 1,396,961.28
  5. Step 5: Solve for x
    x = 1,396,961.28/998.40
  6. Step 6: Final answer
    x = 1,399.20

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.40) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.