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Finding the Fourth Proportional to 811.24, 1,215.90 and 290.80

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Solution

The fourth proportional to 811.24, 1,215.90 and 290.80 is: 435.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.24 : 1,215.90 = 290.80 : x
  2. Step 2: Convert to fraction form
    811.24/1,215.90 = 290.80/x
  3. Step 3: Cross multiply
    811.24x = 1,215.90 × 290.80
  4. Step 4: Simplify right side
    811.24x = 353,583.72
  5. Step 5: Solve for x
    x = 353,583.72/811.24
  6. Step 6: Final answer
    x = 435.86

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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.