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Finding the Fourth Proportional to 998.72, 1,378.08 and 667.64

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Solution

The fourth proportional to 998.72, 1,378.08 and 667.64 is: 921.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    998.72 : 1,378.08 = 667.64 : x
  2. Step 2: Convert to fraction form
    998.72/1,378.08 = 667.64/x
  3. Step 3: Cross multiply
    998.72x = 1,378.08 × 667.64
  4. Step 4: Simplify right side
    998.72x = 920,061.33
  5. Step 5: Solve for x
    x = 920,061.33/998.72
  6. Step 6: Final answer
    x = 921.24

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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.