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Finding the Fourth Proportional to 763.80, 1,145.70 and 215.91

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Solution

The fourth proportional to 763.80, 1,145.70 and 215.91 is: 323.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    763.80 : 1,145.70 = 215.91 : x
  2. Step 2: Convert to fraction form
    763.80/1,145.70 = 215.91/x
  3. Step 3: Cross multiply
    763.80x = 1,145.70 × 215.91
  4. Step 4: Simplify right side
    763.80x = 247,368.09
  5. Step 5: Solve for x
    x = 247,368.09/763.80
  6. Step 6: Final answer
    x = 323.87

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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.