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Finding the Fourth Proportional to 1,398.95, 1,930.79 and 839.87

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Solution

The fourth proportional to 1,398.95, 1,930.79 and 839.87 is: 1,159.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,398.95 : 1,930.79 = 839.87 : x
  2. Step 2: Convert to fraction form
    1,398.95/1,930.79 = 839.87/x
  3. Step 3: Cross multiply
    1,398.95x = 1,930.79 × 839.87
  4. Step 4: Simplify right side
    1,398.95x = 1,621,612.60
  5. Step 5: Solve for x
    x = 1,621,612.60/1,398.95
  6. Step 6: Final answer
    x = 1,159.16

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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.