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Finding the Fourth Proportional to 690.72, 1,036.20 and 203.80

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Solution

The fourth proportional to 690.72, 1,036.20 and 203.80 is: 305.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.72 : 1,036.20 = 203.80 : x
  2. Step 2: Convert to fraction form
    690.72/1,036.20 = 203.80/x
  3. Step 3: Cross multiply
    690.72x = 1,036.20 × 203.80
  4. Step 4: Simplify right side
    690.72x = 211,177.56
  5. Step 5: Solve for x
    x = 211,177.56/690.72
  6. Step 6: Final answer
    x = 305.74

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.