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Finding the Fourth Proportional to 1,290.50, 1,780.95 and 723.39

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Solution

The fourth proportional to 1,290.50, 1,780.95 and 723.39 is: 998.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.50 : 1,780.95 = 723.39 : x
  2. Step 2: Convert to fraction form
    1,290.50/1,780.95 = 723.39/x
  3. Step 3: Cross multiply
    1,290.50x = 1,780.95 × 723.39
  4. Step 4: Simplify right side
    1,290.50x = 1,288,321.42
  5. Step 5: Solve for x
    x = 1,288,321.42/1,290.50
  6. Step 6: Final answer
    x = 998.31

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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.