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Finding the Fourth Proportional to 998.21, 1,377.75 and 643.89

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Solution

The fourth proportional to 998.21, 1,377.75 and 643.89 is: 888.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    998.21 : 1,377.75 = 643.89 : x
  2. Step 2: Convert to fraction form
    998.21/1,377.75 = 643.89/x
  3. Step 3: Cross multiply
    998.21x = 1,377.75 × 643.89
  4. Step 4: Simplify right side
    998.21x = 887,119.45
  5. Step 5: Solve for x
    x = 887,119.45/998.21
  6. Step 6: Final answer
    x = 888.71

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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.