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Finding the Fourth Proportional to 1,398.74, 1,929.75 and 839

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Solution

The fourth proportional to 1,398.74, 1,929.75 and 839 is: 1,157.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,398.74 : 1,929.75 = 839 : x
  2. Step 2: Convert to fraction form
    1,398.74/1,929.75 = 839/x
  3. Step 3: Cross multiply
    1,398.74x = 1,929.75 × 839
  4. Step 4: Simplify right side
    1,398.74x = 1,619,060.25
  5. Step 5: Solve for x
    x = 1,619,060.25/1,398.74
  6. Step 6: Final answer
    x = 1,157.51

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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.