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Finding the Fourth Proportional to 998.51, 1,376.47 and 639.56

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Solution

The fourth proportional to 998.51, 1,376.47 and 639.56 is: 881.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    998.51 : 1,376.47 = 639.56 : x
  2. Step 2: Convert to fraction form
    998.51/1,376.47 = 639.56/x
  3. Step 3: Cross multiply
    998.51x = 1,376.47 × 639.56
  4. Step 4: Simplify right side
    998.51x = 880,340.78
  5. Step 5: Solve for x
    x = 880,340.78/998.51
  6. Step 6: Final answer
    x = 881.65

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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.